PROSITE documentation PDOC00469
HlyD family secretion proteins signature


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 [1,2,3,4,5] 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.

Last update:

December 2004 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

HLYD_FAMILY, PS00543; HlyD family secretion proteins signature  (PATTERN)


1AuthorsGilson L. Mahanty H.K. Kolter R.
TitleGenetic analysis of an MDR-like export system: the secretion of colicin V.
SourceEMBO J. 9:3875-3894(1990).
PubMed ID2249654

2AuthorsLetoffe S. Delepelaire P. Wandersman C.
TitleProtease secretion by Erwinia chrysanthemi: the specific secretion functions are analogous to those of Escherichia coli alpha-haemolysin.
SourceEMBO J. 9:1375-1382(1990).
PubMed ID2184029

3AuthorsStoddard G.W. Petzel J.P. van Belkum M.J. Kok J. McKay L.L.
TitleMolecular analyses of the lactococcin A gene cluster from Lactococcus lactis subsp. lactis biovar diacetylactis WM4.
SourceAppl. Environ. Microbiol. 58:1952-1961(1992).
PubMed ID1622271

4AuthorsDuong F. Lazdunski A. Cami B. Murgier M.
TitleSequence of a cluster of genes controlling synthesis and secretion of alkaline protease in Pseudomonas aeruginosa: relationships to other secretory pathways.
SourceGene 121:47-54(1992).
PubMed ID1427098

5AuthorsLewis K.
TitleMultidrug resistance pumps in bacteria: variations on a theme.
SourceTrends Biochem. Sci. 19:119-123(1994).
PubMed ID8203018

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