{PDOC00469}
{PS00543; HLYD_FAMILY}
{BEGIN}
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* HlyD family secretion proteins signature *
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Gram-negative bacteria  produce  a  number of proteins which are secreted into
the growth medium by a mechanism that  does  not  require a cleaved N-terminal
signal sequence. These proteins, while having different functions, require the
help of two or more proteins  for  their  secretion  across the cell envelope.
Amongst which a  protein  belonging  to  the  ABC transporters family (see the
relevant entry  <PDOC00185>)  and  a  protein  belonging  to a family which is
currently composed [1 to 5] of the following members:

 Gene  Species                  Protein which is exported
 ----  ----------------------   --------------------------------------------
 hlyD  Escherichia coli         Hemolysin
 appD  A.pleuropneumoniae       Hemolysin
 lcnD  Lactococcus lactis       Lactococcin A
 lktD  A.actinomycetemcomitans  Leukotoxin
       Pasteurella haemolytica
 rtxD  A.pleuropneumoniae       Toxin-III
 cyaD  Bordetella pertussis     Calmodulin-sensitive adenylate cyclase-
                                hemolysin (cyclolysin)
 cvaA  Escherichia coli         Colicin V
 prtE  Erwinia chrysanthemi     Extracellular proteases B and C
 aprE  Pseudomonas aeruginosa   Alkaline protease
 emrA  Escherichia coli         Drugs and toxins
 yjcR  Escherichia coli         Unknown

These proteins  are  evolutionary related and consist of from 390 to 480 amino
acid residues. They  seem to be anchored in the inner membrane by a N-terminal
transmembrane region.  Their  exact  role in the  secretion process is not yet
known.

The C-terminal section of these proteins is the best conserved region; we have
derived a signature pattern from that region.

-Consensus pattern: [LIVM]-x(2)-G-[LM]-x(3)-[STGAV]-x-[LIVMT]-x-[LIVMTK]-[GE]-
                    x-[KR]-x-[LIVMFYW](2)-x-[LIVMFYW](2)-[LIVMFYWK]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for emrA and yjcR.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: December 2004 / Pattern and text revised.

[ 1] Gilson L., Mahanty H.K., Kolter R.
     "Genetic analysis of an MDR-like export system: the secretion of
     colicin V."
     EMBO J. 9:3875-3894(1990).
     PubMed=2249654
[ 2] Letoffe S., Delepelaire P., Wandersman C.
     "Protease secretion by Erwinia chrysanthemi: the specific secretion
     functions are analogous to those of Escherichia coli
     alpha-haemolysin."
     EMBO J. 9:1375-1382(1990).
     PubMed=2184029
[ 3] Stoddard G.W., Petzel J.P., van Belkum M.J., Kok J., McKay L.L.
     "Molecular analyses of the lactococcin A gene cluster from Lactococcus
     lactis subsp. lactis biovar diacetylactis WM4."
     Appl. Environ. Microbiol. 58:1952-1961(1992).
     PubMed=1622271
[ 4] Duong F., Lazdunski A., Cami B., Murgier M.
     "Sequence of a cluster of genes controlling synthesis and secretion of
     alkaline protease in Pseudomonas aeruginosa: relationships to other
     secretory pathways."
     Gene 121:47-54(1992).
     PubMed=1427098
[ 5] Lewis K.
     "Multidrug resistance pumps in bacteria: variations on a theme."
     Trends Biochem. Sci. 19:119-123(1994).
     PubMed=8203018

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