Family M90


Summary Holotypes Alignment Tree Genomes Structure Literature

Summary for family M90

Family type peptidaseM90.001 - MtfA peptidase (Escherichia coli), MEROPS Accession MER0217243 (peptidase unit: 1-265)
Content of familyFamily M90 contains aminopeptidases.
History Identifier created: MEROPS 9.7 (1 August 2012)
Family M90 includes the MtfA peptidase (M90.001) from Escherichia coli, also known as the YeeL gene product, which is involved in the control of the glucose-phosphotransferase sensory and regulatory system by inactivation of the repressor Mlc (Gohler et al., 2012).
Catalytic typeMetallo
Active site residuesH148 E149 H152 E211 
Active siteThe crystal structure of the homologue from a Klebsiella species shows the presence of a single zinc ion in the active site ligated by two histidines in an HEXXH motif and a glutamic acid 59 residues C-terminal to this motif (Xu et al., 2012). The glutamic acid of the HEXXH motif is assumed to be a catalytic residue in keeping with other members of clan MA.
Activities and specificitiesAminopeptidase activity was characterized from cleavage of synthetic substrates and lack of cleavage of proteins such as casein (Gohler et al., 2012).
InhibitorsThe metal chelators EDTA and 1,10-phenanthroline inhibit the aminopeptidase activity (Gohler et al., 2012).
Molecular structureThe tertiary structure of a homologue from Klebsiella sp. 4_1_44FAA has been determined (Xu et al., 2012) and has been shown to be related to that of the anthrax lethal factor (M34.001). Hence, family M90 is included in clan MA subclan E. From the structures of the apoenzyme and the active peptidase, activation is controlled by a conformational change of a previously disordered region, centred around Tyr204 (numbered according to the alignment), which completes the active site when zinc binds (Xu et al., 2012).
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi details  
Plants details  
Animals details  
Viruses -  
Biological functionsThe glucose-phosphotransferase system is important for glucose uptake, and in other networks concerned with carbohydrate availability and the physiological status of the cell. The glucose phosphotransferase system transporter EIICB(Glc) is encoded by the ptsG gene, which is regulated by the repressor Mlc. Repressor Mlc inactivation is glucose-dependent. When glucose is being transported, the transporter EIICB(Glc) is dephosphorylated, which allows repressor Mlc to bind to a particular domain, known as the B-domain, of the transporter. Repressor Mlc is depleted from the cytoplasm, which results in the derepression of the genes affected by Mlc. The MtfA peptidase is involved in this pathway by binding to the C-terminal part of Mlc (Gohler et al., 2012). It is not known if MftA cleaves Mlc.
Statistics for family M90Sequences:1056
Identifiers with PDB entries:1
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
MtfA peptidaseM90.001Yes
family M90 non-peptidase homologuesnon-peptidase homologue-
family M90 unassigned peptidasesunassigned-