Article

Membrane proteases in the bacterial protein secretion and quality control pathway.

Department of Chemistry, The Ohio State University, Columbus, Ohio, USA.
Microbiology and molecular biology reviews: MMBR (impact factor: 12.59). 06/2012; 76(2):311-30. DOI:10.1128/MMBR.05019-11 pp.311-30
Source: PubMed

ABSTRACT Proteolytic cleavage of proteins that are permanently or transiently associated with the cytoplasmic membrane is crucially important for a wide range of essential processes in bacteria. This applies in particular to the secretion of proteins and to membrane protein quality control. Major progress has been made in elucidating the structure-function relationships of many of the responsible membrane proteases, including signal peptidases, signal peptide hydrolases, FtsH, the rhomboid protease GlpG, and the site 1 protease DegS. These enzymes employ very different mechanisms to cleave substrates at the cytoplasmic and extracytoplasmic membrane surfaces or within the plane of the membrane. This review highlights the different ways that bacterial membrane proteases degrade their substrates, with special emphasis on catalytic mechanisms and substrate delivery to the respective active sites.

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    Article: Oligomeric state study of prokaryotic rhomboid proteases.
    Padmapriya Sampathkumar, Michelle W Mak, Sarah J Fischer-Witholt, Emmanuel Guigard, Cyril M Kay, M Joanne Lemieux
    [show abstract] [hide abstract]
    ABSTRACT: Rhomboid peptidases (proteases) play key roles in signaling events at the membrane bilayer. Understanding the regulation of rhomboid function is crucial for insight into its mechanism of action. Here we examine the oligomeric state of three different rhomboid proteases. We subjected Haemophilus influenzae, (hiGlpG), Escherichia coli GlpG (ecGlpG) and Bacillus subtilis (YqgP) to sedimentation equilibrium analysis in detergent-solubilized dodecylmaltoside (DDM) solution. For hiGlpG and ecGlpG, rhomboids consisting of the core 6 transmembrane domains without and with soluble domains respectively, and YqgP, predicted to have 7 transmembrane domains with larger soluble domains at the termini, the predominant species was dimeric with low amounts of monomer and tetramers observed. To examine the effect of the membrane domain alone on oligomeric state of rhomboid, hiGlpG, the simplest form from the rhomboid class of intramembrane proteases representing the canonical rhomboid core of six transmembrane domains, was studied further. Using gel filtration and crosslinking we demonstrate that hiGlpG is dimeric and functional in DDM detergent solution. More importantly co-immunoprecipitation studies demonstrate that the dimer is present in the lipid bilayer suggesting a physiological dimer. Overall these results indicate that rhomboids form oligomers which are facilitated by the membrane domain. For hiGlpG we have shown that these oligomers exist in the lipid bilayer. This is the first detailed oligomeric state characterization of the rhomboid family of peptidases.
    Biochimica et Biophysica Acta 08/2012; 1818(12):3090-7. · 4.66 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

bacterial membrane proteases degrade
 
cleave substrates
 
cytoplasmic membrane
 
different mechanisms
 
different ways
 
essential processes
 
extracytoplasmic membrane surfaces
 
Major progress
 
membrane protein quality control
 
proteins
 
respective active sites
 
responsible membrane proteases
 
rhomboid protease GlpG
 
signal peptide hydrolases
 
site 1 protease DegS
 
special emphasis
 
substrate delivery
 
substrates
 
wide range