PMID:8694750

Citation	Gangeswaran, R and Eady, RR (1996) Flavodoxin 1 of Azotobacter vinelandii: characterization and role in electron donation to purified assimilatory nitrate reductase. Biochem. J. 317 ( Pt 1):103-8
Abstract	Flavodoxins synthesized by Azotobacter vinelandii strain UW 36 during growth on nitrate as nitrogen source were separated by FPLC on a Mono Q column into two species, flavodoxin 1 (AvFld 1) and flavodoxin 2 (AvFld 2). Both proteins migrated as single bands on SDS/PAGE. AvFld 1 was approx. 5-fold more abundant than AvFld 2 in the unresolved flavodoxin mixture. N-terminal amino acid analysis showed the sequence of AvFld 2 to correspond to the nif F gene product, an electron donor to nitrogenase. The sequences also show that these species corresponded to the flavodoxins Fld A and Fld B isolated from N2-grown cultures of the closely related organism Azotobacter throococcum [Bagby, Barker, Hill, Eady and Thorneley (1991) Biochem.J.277, 313-319]. Electrospray mass spectrometry gave M, values for the polypeptides of 19430 +/- 3 and 19533 +/- 5 respectively. 31P-NMR measurements showed that in addition to the phosphate associated with the FMN (delta = -136.3 p.p.m. and -135.48 p.p.m.), AvFld 1 had a signal at delta = -142.1 p.p.m. and AvFld 2 at delta = -138.59 p.p.m. present in substoichiometric amounts with FMN. These appeared to arise from unstable species since they were readily lost on further manipulation of the proteins. The mid-point potentials of the semiquinone hydroquinone redox couples were -330 mV and -493 mV for AvFld 1 and AvFld 2 respectively, but only AvFld 1 was competent in donating electrons to the purified assimilatory nitrate reductase of A. vinelandii to catalyse the reduction of nitrate to nitrite. Flavodoxin isolated from NH4(+)-grown cells (Fld 3) also functioned as electron donor at half the rate of AvFld 1, but ferredoxin 1 from A. chroococcum did not.
Links	PubMed PMC1217449
Keywords	Amino Acid Sequence; Azotobacter vinelandii/enzymology; Azotobacter vinelandii/metabolism; Electron Transport; Flavodoxin/metabolism; Hydroquinones/metabolism; Magnetic Resonance Spectroscopy; Molecular Sequence Data; Molecular Weight; Nitrate Reductase; Nitrate Reductases/metabolism; Nitrates/metabolism; Potentiometry; Sequence Analysis
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
9CAUD:S5Y026		GO:0009055: electron carrier activity	ECO:0000247:	UniProtKB:P26492 UniProtKB:Q8VQF4 UniProtKB:Q9UHB4	F		HHPred shows a match with flavodoxin in the Bacterium Desulfovibrio desulfuricans with probability 100.0, e-value 3.5E-29, p value 1E-33. Flavodoxins are proteins that bind flavin mononucleotide(FMN) and are used in electron transfer pathways and redox potentials. PMID:8694750. Blastp showed the presence of conserved regions in the Flavodoxin family of proteins. Given the conservation of the protein and the match with several other proteins, it can be inferred that the protein has a similar structure and function to flavodoxin found in other organisms.	complete CACAO 10824
AZOVI:M9YPU5		GO:0043873: pyruvate-flavodoxin oxidoreductase activity	ECO:0000314:		F		Pubmed article describes the redox potential determined by experimental evidence. The molecule is able to donate electrons to Nitrogen and can accept electrons from pyruvate.	complete CACAO 10890

References

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