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* Beta-lactamases class B signatures *
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Beta-lactamases (EC 3.5.2.6) [1,2]  are enzymes  which catalyze the hydrolysis
of an amide bond in  the  beta-lactam ring  of  antibiotics  belonging  to the
penicillin/cephalosporin  family.  Four  kinds  of  beta-lactamase  have  been
identified [2].  Class-B enzymes are zinc containing proteins whilst class -A,
C and D enzymes  are  serine hydrolases.  Class-B  beta-lactamases  have  been
described in  several  gram-negative bacterial species; they seem to share the
characteristic of  being  able to hydrolyze carbapenem compounds which are new
beta-lactam antibiotics of great therapeutic potential.

There are a number of conserved regions in the sequence of known class-B beta-
lactamases [3]. Some of them are centered on residues known [4] to be involved
in binding  a  zinc  ion  essential  for  the  enzyme's catalytic activity. We
designed two  signature  patterns for this class of enzyme. The first contains
two residues involved in binding the zinc ion as well as a conserved aspartate
residue which  seems  [5]  to  function  as  a  general  base in the catalytic
mechanism. The second pattern contains a cysteine which is also a zinc ligand.

-Consensus pattern: [HN]-x-H-[GSTA]-D-x(2)-G-G-x(7)-G
                    [H/N and H are zinc ligands]
                    [D is a putative active site residue]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Consensus pattern: P-x(3)-[LIVM](2)-x-G-x-C-[LIVM](2)-K
                    [C is a zinc ligand]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Last update: October 1993 / Patterns and text revised.

[ 1] Ambler R.P.
     Phil. Trans. R. Soc. London B 289:321-331(1980).
[ 2] Bush K.
     Antimicrob. Agents Chemother. 33:259-263(1989).
[ 3] Massidda O., Rossolini G.M., Satta G.
     J. Bacteriol. 173:4611-4617(1991).
[ 4] Sutton B.J., Artymiuk P.J., Cordero-Borboa A.E., Little C.,
     Phillips D.C., Waley S.G.
     Biochem. J. 248:181-188(1987).
[ 5] Lim H.M., Iyer R.K., Pene J.J.
     Biochem. J. 276:401-404(1991).