Biology:Exosortase
| Transmembrane exosortase (Exosortase_EpsH) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | Exosortase_EpsH | ||||||||
| Pfam | PF09721 | ||||||||
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Exosortase refers to a family of integral membrane proteins that occur in Gram-negative bacteria that recognizes and cleaves the carboxyl-terminal sorting signal PEP-CTERM.[1][2] The name derives from a predicted role analogous to sortase, despite the lack of any detectable sequence homology, and a strong association of exosortase genes with exopolysaccharide or extracellular polymeric substance biosynthesis loci. Many archaea have an archaeosortase, homologous to exosortases rather than to sortases. Archaeosortase A recognizes the signal PGF-CTERM, found at the C-terminus of some archaeal S-layer proteins. Following processing by archaeosortase A, the PGF-CTERM region is gone, and a prenyl-derived lipid anchor is present at the C-terminus instead.
Exosortase has not itself been characterized biochemically. However, site-directed mutagenesis work on archaeosortase A, an archaeal homolog of exosortases, strongly supports the notion of a Cys active site and convergent evolution with sortase family transpeptidases.[3] A recent study on Zoogloea resiniphila, a bacterium found in activated sludge wastewater treatment plants, has shown that PEP-CTERM proteins (and by implication, exosortase as well) are essential to floc formation in some systems.[4]
References
- ↑ "Exopolysaccharide-associated protein sorting in environmental organisms: the PEP-CTERM/EpsH system. Application of a novel phylogenetic profiling heuristic". BMC Biology 4: 29. August 2006. doi:10.1186/1741-7007-4-29. PMID 16930487.
- ↑ "Archaeosortases and exosortases are widely distributed systems linking membrane transit with posttranslational modification". Journal of Bacteriology 194 (1): 36–48. January 2012. doi:10.1128/JB.06026-11. PMID 22037399.
- ↑ "Conserved residues are critical for Haloferax volcanii archaeosortase catalytic activity: Implications for convergent evolution of the catalytic mechanisms of non-homologous sortases from archaea and bacteria". Molecular Microbiology 108 (3): 276–287. May 2018. doi:10.1111/mmi.13935. PMID 29465796.
- ↑ "Both widespread PEP-CTERM proteins and exopolysaccharides are required for floc formation of Zoogloea resiniphila and other activated sludge bacteria". Environmental Microbiology 20 (5): 1677–1692. May 2018. doi:10.1111/1462-2920.14080. PMID 29473278. http://ir.ihb.ac.cn/handle/342005/29334.
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