Identification of two vicinal operons for the degradation of 2-aminobenzenesulfonate encoded on plasmid pSAH in Alcaligenes sp. strain O-1.
Alcaligenes sp. strain O-1 inducibly deaminates 2-aminobenzenesulfonate (ABS) via dioxygenation to 3-sulfocatechol, which is desulfonated during meta ring-cleavage to yield 2-hydroxymuconate. This intermediate is transformed through the oxalocrotonate-branch of the sulfocatechol meta-pathway (Scm). The complete pathway is encoded on the 180-kb plasmid pSAH, 20kb of which was sequenced. Twenty open reading frames (ORFs) were detected. Two clusters (abs and scm) with degradative genes were surrounded by several transposon-related ORFs. The six genes of the abs cluster were shown to be co-transcribed, and contained the genes for two characterised subunits of the oxygenase component of the ABS-dioxygenase system, and genes putatively encoding ABS-transport functions with similarities to (a) an ABC-type transporter system and (b) a putative major facilitator superfamily transporter. No gene encoding the reductase for the oxygenase system was present in the abs gene cluster, but a candidate gene was found in the scm cluster. The seven-gene scm cluster was also transcribed as single polycistronic message. Functions could be attributed to the gene products, but one enzyme, which was shown to be present, 2-hydroxymuconate isomerase, was not encoded in the scm cluster. No transcriptional regulator was found. This genetic information on the degradation of ABS in strain O-1 provides another example of both split operons and dispersed pathway genes.
Ruff
Jürgen
J
Fachbereich Biologie der Universität Konstanz, Universitätsstrasse 10, D-78457 Konstanz, Germany.
Smits
Theo H M
TH
Cook
Alasdair M
AM
Schleheck
David
D
D000421:Alcaligenes / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004251:DNA Transposable Elements; D005798:Genes, Bacterial; D007535:Isomerases / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D005810:Multigene Family; D009876:Operon; D010957:Plasmids / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013425:Sulfanilic Acids / Q000737:chemistry / Q000378:metabolism*
D004251:DNA Transposable Elements; D013425:Sulfanilic Acids; D007535:Isomerases; C100048:2-sulfanilic acid