Structural aspects of the metzincin clan of metalloendopeptidases

Abstract

Metalloendopeptidases are present across all kingdoms of living organisms; they are ubiquitous and widely involved in metabolism regulation through their ability either to extensively degrade proteins or to selectively hydrolyze specific peptide bonds. They must be subjected to exquisite spatial and temporal control to prevent this vast potential from becoming destructive. These enzymes are mostly zinc-dependent and the majority of them, named zincins, possess a short consensus sequence, HEXXH, with the two histidines acting as ligands of the catalytic zinc and the glutamate as the general base. A subclass of the zincins is characterized by a C-terminally elongated motif, HEXXHXXGXXH/D, with an additional strictly conserved glycine and a third zinc-binding histidine or aspartate. Currently, representative three-dimensional structures of six different proteinase families bearing this motif show, despite low sequence similarity, comparable overall topology. This includes a substrate-binding crevice, which subdivides the enzyme moiety into an upper and a lower subdomain. A common five-stranded beta-sheet and two alpha-helices are always found in the upper subdomain. The second of these helices encompasses the first half of the elongated consensus sequence and is therefore termed the active-site helix. Other shared characteristics are an invariant methionine-containing Met-turn beneath the catalytic metal and a further C-terminal helix in the lower subdomain. All these structural features identify the metzincin clan of metalloendopeptidases. This clan is reviewed from a structural point of view, based on the reported structures of representative members of the astacins, adamalysins, serralysins, matrixins, snapalysins, and leishmanolysins, and of inhibited forms, either by specific endogenous protein inhibitors or by zymogenic pro-domains. Moreover, newly available genomic sequences have unveiled novel putative metzincin families and new hypothetical members of existing ones.

Activity of ulilysin, an archaeal PAPP-A-related gelatinase and IGFBP protease

“…In addition, a potential activesite mutant was generated, in which the putative general base/acid residue Glu229 imbedded in the ZBCS was replaced by alanine (E229A). The alanine mutation of the equivalent glutamate residue in human PAPP-A (Glu483) had been reported to completely abolish activity and similar findings for other metzincins have been published Gomis-Rü th, 2003). The E229 variant did not lead to the above-mentioned biophysical inconveniences of the wild-type construct.…”

“…(large pappalysins). This is reminiscent of other metzincin families such as astacins, MMPs and adamalysins/ADAMs, for which single-and multi-domain sequences have been reported (Bode et al, 1993;Stö cker et al, 1995;Gomis-Rü th, 2003).…”

“…Sequence analysis of PAPP-A and PAPP-A2 further revealed the presence of a conserved methionine residue, as found in what is known as the Met-turn in metzincins. These findings led pappalysins to be assigned to the latter clan (Bode et al, 1993;Stö cker et al, 1995;Gomis-Rü th et al, 1998;Boldt et al, 2001;Gomis-Rü th, 2003;Oxvig et al, 2004).…”

Furin regulates the intracellular activation and the uptake rate of cell surface-associated MT1-MMP

“…Our results agree well with the structural data, which suggest that the R 89 -R-P-R-C 93 site is, in fact, inaccessible to furin in the MT1-MMP proenzyme. The R 89 -R-P-R-C 93 sequence includes the active site Zn 2 þ -binding Cys 93 and this region is shielded from the external proteases by the prodomain sequence (Fernandez-Catalan et al, 1998;Morgunova et al, 1999Morgunova et al, , 2002Gomis-Ruth, 2003).…”

Expression profiling, gene silencing and transcriptional networking of metzincin metalloproteases in the cattle tick, Rhipicephalus (Boophilus) microplus

“…Vector-borne protozoa are known to require these metalloproteases for replication and use them as virulence factors (Barrett et al, 2004;Gomis-Rüth, 2003.) Parasites such as heamatophagous ectoparasites find metzincins essential for reproduction (Bowles et al, 2007;Young et al, 2000) and host infestation (Dzik, 2005;Gallego et al, 2005;Francischetti et al, 2003).…”