Michael Silverman's research while affiliated with La Jolla Bioengineering Institute and other places

Publications (43)

Article
Density-dependent expression of luminescence in Vibrio harveyi is regulated by the concentration of extracellular signal molecules (autoinducers) in the culture medium. One signal-response system is encoded by the luxL,M,N locus. The luxL and luxM genes are required for the production of an autoinducer (probably beta-hydroxybutyl homoserine lactone...
Article
Density-dependent expression of luminescence in Vibrio harveyl is regulated by the concentration of extracellular signal molecules (autoinducers) in the culture medium. One signal-response system is encoded by the luxL,M,N locus. The luxL and luxM genes are required for the production of an autoinducer (probably β-hydroxybutryl homoserine lactone),...
Article
Density-dependent expression of luminescence in Vibrio harveyi is regulated by the concentration of extracellular signal molecules (autoinducers) in the culture medium. A recombinant clone that restored function to one class of spontaneous dim mutants was found to encode a function required for the density-dependent response. Transposon Tn5 inserti...
Article
Density-dependent expression of luminescence in Vibrio harveyi is regulated by the concentration of an extracellular signal molecule (autoinducer) in the culture medium. A recombinant clone that restored function to one class of spontaneous dim mutants was found to encode functions necessary for the synthesis of, and response to, a signal molecule....
Article
Growth of Vibrio parahaemolyticus on the surfaces of solid media induces formation of a specialized bacterium called the swarmer cell. Differentiation to this cell is controlled by an information transduction mechanism which couples perception of signals specific for life on a surface to expression of genes encoding the swarmer cell phenotype. A va...
Article
Bacteria of the genus Vibrio are remarkably diverse, and until recently the methodology for genetic analysis consisted of a patchwork of different approaches, many of which were narrowly applicable to a single species. The invention of the recombinant DNA technology and the subsequent innovations in transposon mutagenesis and in transductive and co...
Article
Vibrio parahaemolyticus distinguishes between life in a liquid environment and life on a surface. Growth on a surface induces differentiation from a swimmer cell to a swarmer cell type. Each cell type is adapted for locomotion under different circumstances. Swimmer cells synthesize a single polar flagellum (Fla) for movement in a liquid medium, and...
Article
Vibrio parahaemolyticus distinguishes between life in a liquid environment and life on a surface. Growth on a surface induces differentiation from a swimmer cell to a swarmer cell type. Each cell type is adapted for locomotion under different circumstances. Swimmer cells synthesize a single polar flagellum (Fla) for movement in a liquid medium, and...
Article
Mutagenesis with transposon mini-Mulac was used previously to identify a regulatory locus necessary for expression of bioluminescence genes, lux, in Vibrio harveyi (M. Martin, R. Showalter, and M. Silverman, J. Bacteriol. 171:2406-2414, 1989). Mutants with transposon insertions in this regulatory locus were used to construct a hybridization probe w...
Article
Full-text available
Vibrio parahaemolyticus synthesizes two distinct flagellar organelles, the polar flagellum (Fla), which propels the bacterium in a liquid environment (swimming), and the lateral flagella (Laf), which are responsible for movement over surfaces (swarming). Chemotactic control of each of these flagellar systems was evaluated separately by analyzing th...
Article
Barophilic bacteria inhabit the deep oceans, and the specific functional modifications and regulatory mechanisms which govern adaptation to hydrostatic pressure are beginning to be understood. For example, the rate of production of several proteins by some hydrothermal vent archaebacteria and the degree of saturation of membrane lipids in other dee...
Article
Mutagenesis with transposon mini-Mulac was used to identify loci containing genes for bioluminescence (lux) in the marine bacterium Vibrio harveyi. Transposon insertions which resulted in a Lux- phenotype were mapped to two unlinked regions of the genome. Region I contained the luxCDABE operon which was previously shown to encode the enzymes lucife...
Article
The complete nucleotide sequence of insertion element IS492, which causes reversible inactivation of extracellular polysaccharide production in the marine bacterium Pseudomonas atlantica, is presented. Insertion of IS492 results in the EPS- phenotype, and excision results in restoration of EPS+. DNA sequencing of the site of insertion in the eps lo...
Article
Full-text available
Vibrio parahaemolyticus has two distinct cell types, the swimmer cell and the swarmer cell, adapted for locomotion in different circumstances. The swimmer cell, produced when the bacterium is grown in liquid media, is a short rod with a single sheathed polar flagellum. The swarmer cell, produced when V. parahaemolyticus is grown on solidified media...
Article
Swarmer cell genes, laf, are induced when V. parahaemolyticus is grown on the surface of solidified media, embedded in solidified media, suspended in viscous media, or agglutinated with antibody in liquid media. These conditions have in common the constraint of the movement of the polar flagellum. To test the hypothesis that the polar flagellum fun...
Article
Production of extracellular polysaccharide by the marine bacterium Pseudomonas atlantica is a variable trait. Strains that produce extracellular polysaccharide (EPS(+)) have a mucoid colony phenotype, but during cultivation in the laboratory nonmucoid, EPS(-) variants arise that have a crenated colony morphology. This change is reversible since cre...
Article
An agarase gene (agrA) was isolated by cloning genomic DNA prepared from Pseudomonas atlantica. The agarase activity in recombinant Escherichia coli was found in cell-free culture supernatants and could pass through a 0.45-mum-pore-size membrane separating cells from agar, suggesting that the gene product was exported in E. coli. The enzyme was spe...
Article
Production of light by the marine bacterium Vibrio fischeri and by recombinant hosts containing cloned lux genes is controlled by the density of the culture. Density-dependent regulation of lux gene expression has been shown to require a locus consisting of the luxR and luxI genes and two closely linked divergent promoters. As part of a genetic ana...
Article
Full-text available
The synthesis of a major outer membrane protein, OmpP, in Vibrio parahaemolyticus was induced by growth in media deficient in phosphate. The gene, ompP, encoding this protein was cloned. Synthesis of OmpP in Escherichia coli was regulated by the availability of phosphate, and this control required the function of pho regulatory genes of E. coli. An...
Article
This chapter discusses the techniques for cloning and analyzing bioluminescence genes from marine bacteria. The isolation by recombinant DNA techniques of genes for bioluminescence (lux) from marine bacteria has resulted in a rapid expansion of knowledge of the biochemical activities necessary for light production and of the regulatory mechanisms,...
Article
Full-text available
Two distinctly different organelles of locomotion are produced by Vibrio parahaemolyticus. The polar flagellum is responsible for motility in a liquid environment (swimming), and the lateral flagella enable the bacteria to move over surfaces (swarming). Synthesis of lateral flagella occurs when V. parahaemolyticus is grown on agar media but not whe...
Article
Light is produced by recombinant Escherichia coli that contain lux genes cloned from the marine bacterium Vibrio fischeri. The bioluminescence phenotype requires genes for regulatory and biochemical functions, the latter encoded by five lux genes contained in a single operon. These lux genes were disconnected from their native promoter and inserted...
Article
Full-text available
Coliphage P1 was used to transduce derivatives of transposons Tn5 and mini-Mu into marine Vibrio spp. Transposon Tn5 encoding tetracycline resistance (Tn5-132) was used to isolate mutants of Vibrio harveyi defective in genes for bioluminescence (lux). Insertion of transposon Tn5-132 into the lux gene region was demonstrated by intraspecific transdu...
Conference Paper
Adhesive substances represent a solution to the problem of colonizing varied surfaces in the bacterial habitat. A given species may have genetic information for a large repertoire of adhesive substances, and the outcome of an encounter between a population of these bacteria and a particular surface may depend on how the bacteria regulate the expres...
Chapter
Adhesive substances represent a solution to the problem of colonizing varied surfaces in the bacterial habitat. A given species may have genetic information for a large repertoire of adhesive substances, and the outcome of an encounter between a population of these bacteria and a particular surface may depend on how the bacteria regulate the expres...
Article
Recombinant E. coli that produce light were found in a clone library of hybrid plasmids containing DNA from the marine bacterium Vibrio fischeri. All luminescent clones had a 16 kb insert that encoded enzymatic activities for the light reaction as well as regulatory functions necessary for expression of the luminescence phenotype (Lux). Mutants gen...
Article
Genes for the luciferase enzyme of Vibrio harveyi were isolated in Escherichia coli by a general method in which nonluminous, transposon insertion mutants were used. Conditions necessary for light production in E. coli were examined. Stimulation of transcription of the genes for luciferase (lux A and lux B) was required for efficient synethesis of...
Article
Phase variation in bacteria is regulated by homologous recombination at a specific DNA site. This recombinational event causes the inversion of a 970-base-pair DNA sequence that includes the promoter necessary for transcription of a flagellar gene. The invertible segment is flanked by two sites that are necessary for the inversion and contains a ge...
Article
Site-specific inversion of a controlling element is responsible for flagellar phase transition in Salmonella. When a 900 bp DNA sequence is in one configuration, it allows the expression of the H2 gene, a structural gene which codes for the flagellar antigen. When it is in the opposite configuration, the H2 gene is not expressed. A hybrid λ phage c...
Article
The products of three chemotaxis-specific genes in Escherichia coli, cheM, cheD, and cheZ, are methylated. The cheZ gene codes for the synthesis of a 24,000 molecular weight polypeptide that appears in the cytoplasm. cheM codes for the synthesis of a membrane-bound polypeptide with a molecular weight of 61,000. cheD codes for another membrane-bound...
Article
Full-text available
In Escherichia coli, the synthesis of the flagellar organelle is sensitive to catabolite repression. Synthesis requires the presence of the cyclic adenosine monophosphate receptor protein (Crp) and 3',5'-cyclic adenosine monophosphate (cAMP); i.e., mutants that lack Crp or adenylcyclase (Cya) synthesize no flagella. We isolated and characterized a...
Article
BACTERIAL flagella are generally composed of three morphologically distinguishable regions: (a) the long flagellar filament which accounts for more than 95% of the flagellar protein; (b) the hook, which is generally 80-90 nm long and has a characteristic shape, and (c) the basal structure which is composed of an intricate set of disks and rods atta...
Article
Full-text available
The distribution of flagellin subunits in flagellar filaments synthesized by merodiploid strains carrying two distinguishable hag loci has been examined. The filament was found to be a homogeneous co-polymer of the two subunits. This suggests that the subunits may be able to mix freely before being assembled.
Article
Full-text available
Two methods were devised to select a series of overlapping deletion mutations carried on episomal elements in Escherichia coli. The deletions were then used in an analysis of (i) the relative position on the genome of previously described mutant loci in the flagellar genes, (ii) the relative position of a newly defined cistron, flaN, and (iii) the...
Article
Full-text available
In previous work, at least 10 discrete cistrons involved in the synthesis of flagella in Escherichia coli were described. Six cistrons were located between his and uvrC on the genetic map. These were referred to as hag, flaA, flaB, flaC, flaD, and flaE. Four cistrons referred to as mot, flaG, flaH, and flaI were located between uvrC and aroD. In or...
Article
Full-text available
Genetic and biochemical analysis of mutants defective in the synthesis of flagella in Escherichia coli revealed an unusual class of mutants. These mutants were found to produce short, curly, flagella-like filaments with low amplitude ( approximately 0.06 mum). The filaments were connected to characteristic flagellar basal caps and extended for 1 to...

Citations

... Since the comprehensive review on this subject by Lawrence et al. in 1995 [1] , significant advances have occurred in this field. The development of molecular tools over the past two decades has expanded our appreciation of the range and genetic basis of surface-induced phenotypes [2,3]. In many instances, the behavior of cells at surfaces exerts a significant impact on system ecology and performance. ...
... If our observations in V. fischeri hold true for other Vibrio species, it may simply be that rounds of growth into stationary phase during genetic manipulations can give rise to luxO* mutants. In this regard, if we consider the reports by Keynan and Hastings (64) and Silverman et al. (65) of "luminescence variation" in V. harveyi resulting in genetically stable dim and dark mutants in old, statically grown cultures, it is tempting to speculate that at least some of these may have been luxO* mutants. One such dark mutant was used in the first description of the luxO locus (66), raising the possibility that a spontaneous luxO* mutant contributed to the discovery of luxO almost 30 years ago (65). ...
... Communication among bacteria using chemical signaling molecules is not a new concept but has been established long ago (1). An established intra-and inter-species cellto-cell communication among bacteria had changed an age-long belief of their existence in planktonic forms without any communication between them. ...
... Genetic rearrangements play a central role in many biological processes, including development (Bostock 1984), gene regulation (Haber 1983;Silverman & Simon 1983;Golden et al. 1987;Stragier et al. 1989), antibody formation (Tonegawa 1983) and evolution (Riley & Anilionis 1978). Rearrangements representing deletions or duplications between repeated sequences, often involving short repeats which are strikingly similar to those found in bacterial rearrangements, have been associated with a number of human diseases. ...
... Current work involves analyzing other clones retrieved directly from the same bank by DNA hybridization as well as examining lineages of opaquetranslucent variants in order to define the molecular basis for the rearrangement. It is possible that switching is the result of a gene or promoter inversion similar to Salmonella typhimurium flagellar phase variation (32) or some kind of phaseshifting event involving the loss of DNA. It is intriguing that the expression of luminescence in V. harveyi is also an unstable phenotype. ...
... In the presence of moisture and nutrients, bacteria attach to surfaces and grow to form extensive films interspersed within extracellular polymer matrices [1,3]. Therefore, biofilms can be defined as matrix-enclosed bacterial populations adherent to each other and/or to surfaces or interfaces [1,2,45678. Compared to their single cell forms one significant consequence of bacteria growing as biofilms is their resistance to medical and industrial control strategies [1,2,89101112131415, which render biofilms of enormous impact on medicine and economy. ...
... There have also been some short reviews describing applications of the lax genes (77,87,124,138). Techniques for cloning the lux genes and screening for the luminescent phenotype have been described in detail (45,95,130); additional methodology is detailed in specific papers. A list of references on the molecular biology of the luminescent systems from different organisms including bacteria has recently been published (137). ...
... Quorum sensing is a cell-to-cell communication mechanism utilized by bacteria to coordinate group behaviors, including bioluminescence production, biofilm formation, bacterial competence, toxin production, and motility (30)(31)(32)(33)(34)(35). Quorum sensing involves the secretion and accumulation of extracellular chemical signals (named autoinducers) as bacterial density increases, recognition of the autoinducers, signal transduction, and regulation of bacterial behavior. ...
... Flagella are organelles whose main function is cell motility. The polar flagellum and lateral flagellum are responsible for swimming motility and swarming motility in V. parahaemolyticus respectively [41]. Deficient swimming motility might be due to downregulation of the polar flagellum in the hutC deletion mutant. ...
... Chemotaxis is intimately linked to bacterial growth and survival and is the key for the movement towards environments containing either higher concentrations of beneficial compounds or lower concentrations of toxic chemicals. The bacterial chemotaxis machinery was firstly identified in E. coli and Salmonella enterica serovar Typhimurium for the regulation of their flagellar-based motility [108][109][110]. Most sequenced bacterial genomes include homologous genes encoding for flagella and chemosensory pathways' components. ...