Correction: A Bacterial Ras-Like Small GTP-Binding Protein and Its Cognate GAP Establish a Dynamic Spatial Polarity Axis to Control Directed Motility

PLoS Biology (Impact Factor: 9.34). 09/2010; 8(9). DOI: 10.1371/annotation/ecce3f2a-35e6-4c27-b444-528248982dbf
Source: PubMed


[This corrects the article on p. e1000430 in vol. 8.].

Download full-text


Available from: Yong Zhang
  • [Show abstract] [Hide abstract]
    ABSTRACT: A PWM power amplifier which constitutes the feedback-control system so that the output voltage supplied to load might be proportional to a reference input is used as amplifier itself or as power supply. Then, a robust PWM power amplifier-whose transient, response characteristics do not, deteriorate to an extensive load change or direct-current power-supply voltage change is needed. Moreover. the. amplifier output. rarest be made to follow its reference input correctly in the application of an amplifier as a power supply which generates various functions. Therefore, the band width of amplifier must be specified, and, at the same time, an over-shoot in a step response is not allowed. In this paper. a. method for designing a robust controller of PWM power amplifier is proposed which can satisfy such demands. The controller constitutes an approximate 2-degree-of-freedom integral type servo system. This servo system becomes fully robust against a. large load change. Moreover. the controller obtained by this designing method is actually manufactured, and it is shown. from an experiment that a sufficiently robust control system is realizable
    No preview · Conference Paper · Feb 2000
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The mglA gene from the bacterium Myxococcus xanthus encodes a 22kDa protein related to the Ras superfamily of monomeric GTPases. MglA is required for the normal function of A-motility (adventurous), S-motility (social), fruiting body morphogenesis, and sporulation. MglA and its homologs differ from all eukaryotic and other prokaryotic GTPases because they have a threonine (Thr78) in place of the highly conserved aspartate residue of the consensus PM3 (phosphate-magnesium binding) region. To identify residues critical for MglA function or potential protein interactions, and explore the function of Thr78, the phenotypes of 18 mglA mutants were characterized. Nine mutants, with mutations predicted to alter residues that bind the guanine base or coordinate magnesium, did not produce detectable MglA. As expected, these mutants were mot- dev- because MglA is essential for these processes. Of the remaining nine mutants, seven showed a wild-type distribution pattern for MglA but fell into two categories with regard to function. Five of the seven mutants exhibited mild phenotypes, but two mutants, T78D and P80A, abolished motility and development. The localization pattern of MglA was abolished in two mutants that were mot- spo- and dev-. These two mutants were predicted to alter surface residues at Asp52 and Thr54, which suggests that these residues are critical for proper localization and may define a protein interaction site. Improving the consensus match with Ras at Thr78 abolished function of MglA. Only the conservative serine substitution was tolerated at this position. Merodiploid constructs revealed that a subset of alleles, including mglAD52A, were dominant and also illustrated that changing the balance of MglA and its co-transcribed partner, MglB, affects A-motility. Our results suggest that GTP binding is critical for stability of MglA because MglA does not accumulate in mutants that cannot bind GTP. The threonine in PM3 of MglA proteins represents a novel modification of the highly conserved GTPase consensus at this position. The requirement for a hydroxyl group at this position may indicate that MglA is subject to modification under certain conditions. Proper localization of MglA is critical for both motility and development and likely involves protein interactions mediated by residues Asp52 and Thr54.
    Full-text · Article · Nov 2010 · BMC Microbiology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Protein-directed intracellular transport has not been observed in bacteria despite the existence of dynamic protein localization and a complex cytoskeleton. However, protein trafficking has clear potential uses for important cellular processes such as growth, development, chromosome segregation, and motility. Conflicting models have been proposed to explain Myxococcus xanthus motility on solid surfaces, some favoring secretion engines at the rear of cells and others evoking an unknown class of molecular motors distributed along the cell body. Through a combination of fluorescence imaging, force microscopy, and genetic manipulation, we show that membrane-bound cytoplasmic complexes consisting of motor and regulatory proteins are directionally transported down the axis of a cell at constant velocity. This intracellular motion is transmitted to the exterior of the cell and converted to traction forces on the substrate. Thus, this study demonstrates the existence of a conserved class of processive intracellular motors in bacteria and shows how these motors have been adapted to produce cell motility.
    Full-text · Article · May 2011 · Proceedings of the National Academy of Sciences
Show more