Electron transfer protein for anaerobic sulfite reductase subunit A.

MAIKITPDEFSLLIQRLNKKWRVFAPSAEFRGGRFSDTDNIIYQRISGWRDLIWHEKSHM SPNTIIAPITETLFYFDKDTIQIAETDTSPIIIFARACDINAMSRLDYMYLSNGNNSDYS YQLLREHIRFVLIECEESFENCFCVSMGTNKTDCYSAAMRFSDEGALVSIRDPFIEAAIQ GLGQEADYTPSFVSENRETVVTPDSVCHDPQKIRDILTHHPLWDAYDSRCISCGRCTTGC PTCTCYSVFDVAYDENPQRGERRRQWASCMVPGFSDMAGGHGFREKPGERLRYRALHKVN DYKARNGIEHMCVGCGRCDDRCPQYIKFSLIINKMTAAVRQALAEEA352

	PMID	Title & Author	Abstract	Year
0	1704886	Sequence analysis and expression of the Salmonella typhimurium asr operon encoding production of hydrogen sulfide from sulfite C J Huang , E L Barrett	A chromosomal locus of Salmonella typhimurium which complements S. typhimurium asr (anaerobic sulfite reduction) mutants and confers on Escherichia coli the ability to produce hydrogen sulfide from sulfite was recently cloned (C. J. Huang and E. L. Barrett, J. Bacteriol. 172:4100-4102, 1990). The DNA sequence and the transcription start site have been determined. Analysis of the sequence and gene products revealed a functional operon containing three genes which have been designated asrA, asrB, and asrC, encoding peptides of 40, 31, and 37 kDa, respectively. The predicted amino acid sequences of both asrA and asrC contained arrangements of cysteines characteristic of [4Fe-4S] ferredoxins. The sequence of asrB contained a typical nucleotide-binding region. The sequence of asrC contained, in addition to the ferredoxinlike cysteine clusters, two other cysteine clusters closely resembling the proposed siroheme-binding site in biosynthetic sulfite reductase. Expression of lacZ fused to the asr promoter was repressed by oxygen and induced by sulfite. Analysis of promoter deletions revealed a region specific for sulfite regulation and a second region required for anaerobic expression. Computer-assisted DNA sequence analysis revealed a site just upstream of the first open reading frame which had significant homology to the FNR protein-binding site of E. coli NADH-linked nitrite reductase. However, asr expression by the fusion plasmid was not affected by site-specific mutations within the apparent FNR-binding site.	1991
1	10231485	The genetic basis of tetrathionate respiration in Salmonella typhimurium M Hensel , A P Hinsley, T Nikolaus, G Sawers, B C Berks	A range of bacteria are able to use tetrathionate as a terminal respiratory electron acceptor. Here we report the identification and characterization of the ttrRSBCA locus required for tetrathionate respiration in Salmonella typhimurium LT2a. The ttr genes are located within Salmonella pathogenicity island 2 at centisome 30.5. ttrA, ttrB and ttrC are the tetrathionate reductase structural genes. Sequence analysis suggests that TtrA contains a molybdopterin guanine dinucleotide cofactor and a [4Fe-4S] cluster, that TtrB binds four [4Fe-4S] clusters, and that TtrC is an integral membrane protein containing a quinol oxidation site. TtrA and TtrB are predicted to be anchored by TtrC to the periplasmic face of the cytoplasmic membrane implying a periplasmic site for tetrathionate reduction. It is inferred that the tetrathionate reductase, together with thiosulphate and polysulphide reductases, make up a previously unrecognized class of molybdopterin-dependent enzymes that carry out the reductive cleavage of sulphur-sulphur bonds. Cys-256 in TtrA is proposed to be the amino acid ligand to the molybdopterin cofactor. TtrS and TtrR are the sensor and response regulator components of a two-component regulatory system that is absolutely required for transcription of the ttrBCA operon. Expression of an active tetrathionate reduction system also requires the anoxia-responsive global transcriptional regulator Fnr. The ttrRSBCA gene cluster confers on Escherichia coli the ability to respire with tetrathionate as electron acceptor.	1999

Huang C J , Barrett E L . Sequence analysis and expression of the Salmonella typhimurium asr operon encoding production of hydrogen sulfide from sulfite.[J]. Journal of Bacteriology, 1991, 173(4):1544-1553.