Disease relevance of algA

• Chromosomal DNA from group I Pseudomonas species, Azotobacter vinelandii, Azomonas macrocytogens, Xanthomonas campestris, Serpens flexibilis, and three enteric bacteria was screened for sequences homologous to four Pseudomonas aeruginosa alginate (alg) genes (algA, pmm, algD, and algR1) [1].
• An open reading frame in the Rhodospirillum rubrum plasmid, pKY1, similar to algA, encoding the bifunctional enzyme phosphomannose isomerase-guanosine diphospho-D-mannose pyrophosphorylase (PMI-GMP) [2].

High impact information on algA

• DNA sequencing of a cloned mutant algA gene from P. aeruginosa revealed that a point mutation at nucleotide 961 greatly decreased the levels of both PMI and GMP in a crude extract [3].
• We present here the characterization of the A. vinelandii chromosomal region comprising algD and its promoter region, algA and algL, showing that, as previously reported for P. aeruginosa, A. vinelandii has a cluster of the biosynthetic alginate genes [4].
• Northern blot hybridization experiments also showed that a transposon insertion downstream of algD adversely affected algG and algA transcription [5].
• An algF mutant failed to produce alginate owing to a polar effect on the downstream algA gene [6].
• A broad-host-range plasmid containing the entire alginate gene cluster except for the terminal gene, algA, was unable to complement an alG::Tn501 mutant unless algA was transcribed from a second plasmid [5].

Chemical compound and disease context of algA

• A significant similarity was found between the amino acid sequences deduced from the nucleotide sequence of BglII fragment with that of algA, encoding the bifunctional enzyme with both the activities of phosphomannose isomerase and guanosine diphospho-D-mannose pyrophosphorylase of Pseudomonas aeruginosa [2].

Biological context of algA

• These results demonstrated that algF, a gene involved in alginate acetylation, is located directly upstream of algA [7].
• By gene replacement, DNA with a Tn501 insertion directly upstream of algA was recombined with the chromosome of mucoid strain FRD1 [7].
• X. campestris contained sequences homologous to pmm and algR1 but not to algA or algD [1].
• This mutant (alm1) had a nonmucoid phenotype due to a polar effect on the transcription of an essential alg gene, algA [8].
• Through genetic analysis, we previously identified algF, located upstream of algA in the 18-kb alginate biosynthetic operon, as a gene required for alginate acetylation [9].

Other interactions of algA

• Nevertheless, no transcripts homologous to algA (encoding a bifunctional enzyme that possesses both PMI and GMP activities) were detected in the nonmucoid form, and the levels of algC (encoding PMM) transcripts, although detectable in the nonmucoid variants, were, in general, much higher in the mucoid forms [10].

Analytical, diagnostic and therapeutic context of algA

• Amino acids that are required for the GMP enzyme activity were identified through site-directed mutagenesis of the algA gene [11].

References