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EcogeneTopic Page
TopicPage for Murein hydrolases of Escherichia coli K-12
 | Murein biosynthesis and degradation |
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Description:
There are 24 murein hydrolases in E. coli K-12, including the three recently characterized DD-endopeptidases Spr, YdhO and YebA, any one of which is essential for the peptidoglycan hydrolase activity essential for bacterial growth and elongation of the murein chain (Singh, 2012). 13 other periplasmic murein hydrolases (autolysins) remodel and degrade peptidoglycan during growth but are not essential for growth. Murein biosynthesis may be regulated by the cytoskeleton. 8 additional murein hydrolases in the inner membrane and cytoplasm assist in murein biosynthesis, recycling, cell separation and flagellar synthesis.
Details:
The 13 periplasmic murein hydrolases are autolysins capable of degrading murein to fragments. They include five outer membrane lipoprotein lytic transglycosylase muramidases MltABCD, EmtA(MltE) and one soluble lytic transglycosylase Slt. There is also a recently described OM-associated non-lipoprotein lytic transglycoslylase MltF. There are also three periplasmic N-acetylmuramyl-L-alanine amidases AmiABC and three periplasmic endopeptidases: MepA and the membrane-associated periplasmic PBPs DacB(PBP4) and PbpG(PBP7). There are three cytoplasmic murein hydrolases involved in murein recycling: AmpD, NagZ and LdcA and three inner membrane PBPs that are murein hydrolases: DacACD. EnvC is a murein hydrolase at the septation site involved in cell separatio. FlgJ is a flagellum-asociated murein hydrolase presumably assisting flagellar extrusion through the murein layer.
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