Archaeosortase
An archaeosortase is a protein that occurs in the cell membranes of some archaea.[1] Archaeosortases recognize and remove carboxyl-terminal protein sorting signals about 25 amino acids long from secreted proteins. A genome that encodes one archaeosortase may encode over fifty target proteins. The best characterized archaeosortase target is the Haloferax volcanii S-layer glycoprotein, an extensively modified protein with O-linked glycosylations, N-linked glycosylations, and a large prenyl-derived lipid modification toward the C-terminus.[2] It remains unclear if archaeosortase is a protease that simply removes the C-terminal segment , or a transpeptidase that attaches a lipid moiety in its place.
Archaeosortases are related to exosortases, their counterparts in Gram-negative bacteria. The names of both families of proteins reflect roles analogous to sortases in Gram-positive bacteria, with which they share no sequence homology. The sequences of archaeosortases and exosortases consists mostly of hydrophobic transmembrane helices, which sortases lack. Archaeosortases fall into a number of distinct subtypes, each responsible for recognizing sorting signals with a different signature motif. Archaeosortase A (ArtA) recognizes the PGF-CTERM signal, ArtB recognizes VPXXXP-CTERM, AtrC recognizes PEF-CTERM, and so on; one archaeal genome may encode two different archaeosortase systems.
References
- ↑ Haft, Daniel H.; Samuel H. Payne; Jeremy D. Selengut (January 2012). "Archaeosortases and Exosortases Are Widely Distributed Systems Linking Membrane Transit with Posttranslational Modification". J. Bacteriol. 194 (1): 36–48. doi:10.1128/JB.06026-11.
- ↑ "Haloferax volcanii archaeosortase is required for motility, mating, and C-terminal processing of the S-layer glycoprotein" 88 (6). Jun 2013. pp. 1164–75. doi:10.1111/mmi.12248. PMID 23651326.