{PDOC51772}
{PS51772; ACD}
{BEGIN}
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* Actin cross-linking (ACD) domain profile *
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Actin cross-linking  domains  (ACDs)  are  distinct  domains  found in several
bacterial toxins,  including  the Vibrio cholerae MARTX toxin. ACDs are enzyme
ligases that catalyze the formation of an irreversible iso-peptide bond on two
actin molecules  in  an  ATP-  and  Mg/Mn(2+)-dependent  manner. Cross-linking
depletes the   cellular   pool   of  G-actin  leading  to  actin  cytoskeleton
depolymerization [1,2].

The ACD has an overall V-shape. with the active site composed of five residues
in a  cleft  located  within the two arms of the V (see <PDB:4DTD>). The first
subdomain, forming  the left arm of the V, is mainly composed of beta-strands,
while the  second  subdomain,  forming the right arm of the V, is helical. The
first subdomain  is  composed of a central anti-parallel beta-sheet of 8 beta-
strands, decorated  by  two  adjacent small beta-sheets, one above the central
beta-sheet and  the  second below. A long helix (alpha1) packs against strands
beta7-beta4-beta5 from the central beta-sheet, and strand beta8 from the upper
beta-sheet. Finally, the terminal helix alpha9 packs against strands beta2 and
beta9. The second subdomain is composed of 7 alpha-helices (alpha2-alpha8) and
does not contain any beta-strands [2].

The profile we developed covers the entire ACD domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: August 2015 / First entry.

[ 1] Geissler B., Bonebrake A., Sheahan K.-L., Walker M.E., Satchell K.J.F.
     "Genetic determination of essential residues of the Vibrio cholerae
     actin cross-linking domain reveals functional similarity with
     glutamine synthetases."
     Mol. Microbiol. 73:858-868(2009).
     PubMed=19656298; DOI=10.1111/j.1365-2958.2009.06810.x
[ 2] Durand E., Derrez E., Audoly G., Spinelli S., Ortiz-Lombardia M.,
     Raoult D., Cascales E., Cambillau C.
     "Crystal structure of the VgrG1 actin cross-linking domain of the
     Vibrio cholerae  type VI secretion system."
     J. Biol. Chem. 287:38190-38199(2012).
     PubMed=22898822; DOI=10.1074/jbc.M112.390153

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