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Detection, isolation, and characterisation of siderophores.
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2. NAHLIK, M.S., BRICKMAN, T.J., OZENBERGER, B.A. AND MCINTOSH, M.A.
Nucleotide sequence and transcriptional organisation of the Escherichia
coli enterobactin biosynthesis cistrons entB and entA.
J.BACTERIOL. 171 784-790 (1989).
3. WYCKOFF, E.E., STOEBNER, J.A., REED, K.E. AND PAYNE, S.M.
Cloning of a Vibrio cholera vibriobactin gene cluster: identification of
genes required for early steps in siderophore synthesis.
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4. LIU, J., DUNCAN, K. AND WALSH, C.T.
Nucleotide sequence of a cluster of Escherichia coli enterobactin
biosynthesis genes: identification of entA and purification of its product
J.BACTERIOL. 171 791-798 (1989).
Iron is essential for growth in both bacteria and mammals. Controlling the
amount of free iron in solution is often used as a tactic by hosts to limit
invasion of pathogenic microbes; binding iron tightly within protein
molecules can accomplish this. Such iron-protein complexes include haem in
blood, lactoferrin in tears/saliva and transferrin in blood plasma. Some
bacteria express surface receptors to capture eukaryotic iron-binding
compounds, while others have evolved siderophores to scavenge iron from
iron-binding host proteins .
The absence of free iron molecules in the surrounding environment triggers
transcription of gene clusters that encode both siderophore-synthesis
enzymes, and receptors that recognise iron-bound siderophores . Classic
examples are the enterobactin/enterochelin clusters found in Escherichia
coli and Salmonella spp., although similar moieties in other pathogens have
been identified. The enzymic machinery that produces vibrionectin in Vibrio
cholera is such a homologue .
EntA, a 2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase enzyme, is involved
in the third stage of enterobactin biosynthesis and converts isochorismate
to 2,3-dihydroxybenzoic acid (DHBA). Deletion studies involving EntA-
mutants have shown that it is essential for virulence .
DHBDHDRGNASE is a 6-element fingerprint that provides a signature for
2,3-dihydro-2,3-dihydroxybenzoate dehydrogenases. The fingerprint was
derived from an initial alignment of 3 sequences: the motifs were drawn
from conserved regions spanning the full alignment length. A single
iteration on SPTR37_10f was required to reach convergence, no further
sequences being identified beyond the starting set.
DHBA_BACSU 2,3-DIHYDRO-2,3-DIHYDROXYBENZOATE DEHYDROGENASE (EC 188.8.131.52) (COLD SHOCK PROTEIN CSI14) - BACILLUS SUBTILIS.
ENTA_ECOLI 2,3-DIHYDRO-2,3-DIHYDROXYBENZOATE DEHYDROGENASE (EC 184.108.40.206) - ESCHERICHIA COLI.
VIBA_VIBCH VIBRIOBACTIN-SPECIFIC 2,3-DIHYDRO-2,3-DIHYDROXYBENZOATE DEHYDROGENASE (EC 220.127.116.11) - VIBRIO CHOLERAE.