| Literature References | 1. OELSCHLAEGER, T.A., DOBRINDT, U. AND HACKER, J.
Virulence factors of uropathogens.
CURR.OPIN.UROL. 12 33-38 (2002).
2. SELTMANN, G. AND WOLTER, E.J.
Localization of a streptothricin acetyl transferase in cells of Escherichia
coli K-12.
J.BASIC MICROBIOL. 25 197-2012 (1985).
3. OGASAWARA, N., NAKAI, S. AND YOSHIKAWA, H.
Systemic sequencing of the 180 kilobase region of the Bacillus subtilis
chromosome containing the replication origin.
DNA RES. 1 1-14 (1994).
4. FERNANDEZ-MORENO, M.A., VALLIN, C. AND MALPARTIDA, F.
Streptothricin biosynthesis is catalysed by enzymes related to nonribosomal
peptide bond formation.
J.BACTERIOL. 179 6929-6936 (1997).
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| Documentation | A small number of bacterial pathogens are implicated in urinary tract
infections (UTIs), amongst the most frequent infections in the developed
world. The commonest bacterium isolated from UTI is Escherichia coli, with
streptococcal and staphylococcal species coming a close second [1]. Virulent
microbes that colonise the human urinary tract usually possess sets of
virulence factors specific to the host environment [1]. The most common are
adhesins, molecules that allow an infection to become established; well-
characterised E.coli type I pili are a good example.
Aside from adhesins, other UTI-specific virulence moieties include: toxins,
such as Cnf1 and hemolysin, and host biocides that act against other
microbes competing for the same niche [1]. Streptothricin, an antibiotic
synthesised and secreted by some Gram-negative pathogens, is an example of
the latter [2]; the antibiotic also has a toxic effect on host cells. The
biocide is synthesised in a five-step process in the bacterial cytoplasm,
and secreted to the cell exterior via the general secretory pathway [2,3].
The last step in the synthesis process is the acetyl co-enzyme A-dependent
acetylation of the streptothricin molecule to the mature antibiotic. This is
catalysed by the streptothricin acetyltransferase protein, located adjacent
to the inner face of the cytoplasmic membrane [2,3]. Homologues of the
original gene found in Streptomyces spp. have been found in Bacillus
subtilis and Staphylococcus spp., as well as E.coli [2,3]. More recently,
the streptothricin biosynthesis enzymes were shown to be related to those
that carry out non-ribosomal peptide bond formation [4].
SACTRNSFRASE is a 4-element fingerprint that provides a signature for the
streptothricin acetyltransferases. The fingerprint was derived from an
initial alignment of 5 sequences: the motifs were drawn from conserved
regions spanning the C-terminal portion of the alignment (~90 amino acids).
Two iterations on SPTR40_20f were required to reach convergence, at which
point a true set comprising 6 sequences was identified. Three partial
matches were also found, Q47625, O33583 and Q08414, all of which are related
streptothricin/nourseothricin acetyltransferases that match two motifs.
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