{PDOC50911}
{PS50911; CHAP}
{BEGIN}
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* CHAP domain profile *
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The CHAP  (cysteine, histidine-dependent amidohydrolases/peptidases) domain is
a region  between  110  and  140  amino  acids  that is found in proteins from
bacteria, bacteriophages, archaea and eukaryotes of the Trypanosomidae family.
Many of these proteins are uncharacterized, but it has been proposed that they
may function mainly in peptidoglycan hydrolysis. The CHAP domain is found in a
wide range  of protein architectures; it is commonly associated with bacterial
type SH3  domains  and  with  several families of amidase domains. It has been
suggested that  CHAP  domain  containing proteins utilize a catalytic cysteine
residue in a nucleophilic-attack mechanism [1,2].

The CHAP  domain  contains two invariant residues, a cysteine and a histidine.
These residues form part of the putative active site of CHAP domain containing
proteins. Secondary structure predictions show that the CHAP domain belongs to
the alpha + beta structural class, with the N-terminal half largely containing
predicted alpha  helices  and  the  C-terminal  half  principally  composed of
predicted beta strands [1,2].

Some proteins known to contain a CHAP domain are listed below:

 - Bacterial and trypanosomal glutathionylspermidine amidases.
 - A variety of bacterial autolysins.
 - A Nocardia aerocolonigene putative esterase.
 - Streptococcus pneumoniae choline-binding protein D.
 - Methanosarcina mazei protein MM2478, a putative chloride channel.
 - Several phage-encoded peptidoglycan hydrolases.

The profile we developed covers the entire CHAP domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: June 2003 / First entry.

[ 1] Rigden D.J., Jedrzejas M.J., Galperin M.Y.
     "Amidase domains from bacterial and phage autolysins define a family
     of gamma-D,L-glutamate-specific amidohydrolases."
     Trends Biochem. Sci. 28:230-234(2003).
     PubMed=12765833
[ 2] Bateman A., Rawlings N.D.
     "The CHAP domain: a large family of amidases including GSP amidase and
     peptidoglycan hydrolases."
     Trends Biochem. Sci. 28:234-237(2003).
     PubMed=12765834

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