| Literature References | 1. BIEKER, K.L., PHILLIPS, G.J. AND SILHAVY, T.J.
The sec and prl genes of Escherichia coli.
J.BIOENERG.BIOMEMBR. 22 291-310 (1990).
2. SCOTTI, P.A., URBANUS, M.L., BRUNNER, J., DE GIER, J-W.L., VON HEIJNE, G.,
VAN DER DOES, C., DRIESSEN, A.J., OUDEGA, B. AND LUIRINK, J.
YidC, the Escherichia coli homologue of mitochondrial Oxa1p, is a component
of the Sec translocase.
EMBO J. 19 542-549 (2000).
3. VAN DER LAAN, M., HOUBEN, E.N., NOUWEN, N., LUIRINK, J. AND DRIESSEN, A.J.
Reconstitution of Sec-dependent membrane protein insertion: nascent FtsQ
interacts with YidC in a SecYEG-dependent manner.
EMBO REP. 2 519-523 (2001).
4. NOUWEN, N. AND DRIESSEN, A.J.
SecDFyajC forms a heterotetrameric complex with YidC.
MOL.MICROBIOL. 44 1397-1405 (2002).
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| Documentation | Secretion across the inner membrane in some Gram-negative bacteria occurs
via the preprotein translocase pathway. Proteins are produced in the
cytoplasm as precursors, and require a chaperone subunit to direct them to
the translocase component [1]. From there, the mature proteins are either
targeted to the outer membrane, or remain as periplasmic proteins [1]. The
translocase protein subunits are encoded on the bacterial chromosome.
The translocase itself comprises 7 proteins, including a chaperone (SecB),
ATPase (SecA), an integral membrane complex (SecY, SecE and SecG), and two
additional membrane proteins that promote the release of the mature peptide
into the periplasm (SecD and SecF) [1]. Other cytoplasmic/periplasmic
proteins play a part in preprotein translocase activity, namely YidC and
YajC [2]. The former is involved in the insertion of hydrophobic sequences
into the lipid bilayer after recognition by the SecYEG membrane complex [2].
YidC itself is a homologue of the Saccharomyces cerevisiae Oxa1p, a
mitochondrial inner membrane protein that facilitates export from the
organelle [2]. Other similarities have been found between YidC, sporulation
proteins from Bacillus spp., and Gram-negative bacterial 60kDa inner
membrane moieties, suggesting a common ancestor for these translocation
pathway proteins [3].
Recently, the precise interactions between the E.coli SecYEG complex,
SecD, SecF, and the two essential membrane proteins YajC and YidC, have
been researched [4]. Rather than acting individually, the four proteins form
a heterotetrameric complex and associate with the SecYEG heterotrimeric
complex [4].
YIDCPROTEIN is a 3-element fingerprint that provides a signature for the
YidC translocation/secretion protein family. The fingerprint was derived
from an initial alignment of 10 sequences: the motifs were drawn from
conserved regions spanning the C-terminal portion of the alignment. Two
iterations on SPTR40_20f were required to reach convergence, at which point
a true set comprimising 33 sequences was identified. Two partial matches
were also found, both of which are related Bacillus sporulation proteins.
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