Limits...
Role of a Fur homolog in iron metabolism in Nitrosomonas europaea.

Vajrala N, Sayavedra-Soto LA, Bottomley PJ, Arp DJ - BMC Microbiol. (2011)

Bottom Line: Unlike the wild type, the fur:kanP mutant was capable of utilizing iron-bound ferrioxamine without any lag phase and showed over expression of several outer membrane TonB-dependent receptor proteins irrespective of Fe availability.Our studies have clearly indicated a role in Fe regulation by the Fur protein encoded by N. europaea NE0616 gene.Additional studies are required to fully delineate role of this fur homolog.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Botany and Plant Pathology, 2082 Cordley, Oregon State University, Corvallis, OR 97331, USA.

ABSTRACT

Background: In response to environmental iron concentrations, many bacteria coordinately regulate transcription of genes involved in iron acquisition via the ferric uptake regulation (Fur) system. The genome of Nitrosomonas europaea, an ammonia-oxidizing bacterium, carries three genes (NE0616, NE0730 and NE1722) encoding proteins belonging to Fur family.

Results: Of the three N. europaea fur homologs, only the Fur homolog encoded by gene NE0616 complemented the Escherichia coli H1780 fur mutant. A N. europaea fur:kanP mutant strain was created by insertion of kanamycin-resistance cassette in the promoter region of NE0616 fur homolog. The total cellular iron contents of the fur:kanP mutant strain increased by 1.5-fold compared to wild type when grown in Fe-replete media. Relative to the wild type, the fur:kanP mutant exhibited increased sensitivity to iron at or above 500 μM concentrations. Unlike the wild type, the fur:kanP mutant was capable of utilizing iron-bound ferrioxamine without any lag phase and showed over expression of several outer membrane TonB-dependent receptor proteins irrespective of Fe availability.

Conclusions: Our studies have clearly indicated a role in Fe regulation by the Fur protein encoded by N. europaea NE0616 gene. Additional studies are required to fully delineate role of this fur homolog.

Show MeSH

Related in: MedlinePlus

SDS-PAGE Analysis of total membrane proteins. N. europaea wild type and fur:kanP mutant in Fe-replete (10 μM) (lanes 1, 3) and Fe-limited (0.2 μM) media (lanes 2, 4). Over-expression of proteins with molecular weights similar to outer membrane Fe-siderophore receptors indicated by * was observed in fur:kanP mutant in both Fe-replete and Fe-limited media.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3050691&req=5

Figure 6: SDS-PAGE Analysis of total membrane proteins. N. europaea wild type and fur:kanP mutant in Fe-replete (10 μM) (lanes 1, 3) and Fe-limited (0.2 μM) media (lanes 2, 4). Over-expression of proteins with molecular weights similar to outer membrane Fe-siderophore receptors indicated by * was observed in fur:kanP mutant in both Fe-replete and Fe-limited media.

Mentions: Previous studies have shown that N. europaea grown in Fe-limited medium stimulated expression of several Fe-regulated outer membrane proteins (TonB-dependent receptors) with molecular masses of ~ 80 kDa [13,14]. To determine whether the expression of these proteins was regulated by fur, the N. europaea wild type and the fur:kanP mutant strains were cultured in Fe-replete and Fe-limited media and their total outer membrane proteins were isolated. SDS-PAGE analysis of the outer membrane protein profiles demonstrated that fur:kanP mutant shared a major protein band (Figure 6) with wild type cells grown in Fe-limited media irrespective of the concentration of iron in the medium. This band contained several TonB-dependent OM Fe3+-siderophore receptors [13,14]. This result is consistent with the model in which the TonB-dependent receptors with putative roles in iron uptake are regulated by fur [6].


Role of a Fur homolog in iron metabolism in Nitrosomonas europaea.

Vajrala N, Sayavedra-Soto LA, Bottomley PJ, Arp DJ - BMC Microbiol. (2011)

SDS-PAGE Analysis of total membrane proteins. N. europaea wild type and fur:kanP mutant in Fe-replete (10 μM) (lanes 1, 3) and Fe-limited (0.2 μM) media (lanes 2, 4). Over-expression of proteins with molecular weights similar to outer membrane Fe-siderophore receptors indicated by * was observed in fur:kanP mutant in both Fe-replete and Fe-limited media.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3050691&req=5

Figure 6: SDS-PAGE Analysis of total membrane proteins. N. europaea wild type and fur:kanP mutant in Fe-replete (10 μM) (lanes 1, 3) and Fe-limited (0.2 μM) media (lanes 2, 4). Over-expression of proteins with molecular weights similar to outer membrane Fe-siderophore receptors indicated by * was observed in fur:kanP mutant in both Fe-replete and Fe-limited media.
Mentions: Previous studies have shown that N. europaea grown in Fe-limited medium stimulated expression of several Fe-regulated outer membrane proteins (TonB-dependent receptors) with molecular masses of ~ 80 kDa [13,14]. To determine whether the expression of these proteins was regulated by fur, the N. europaea wild type and the fur:kanP mutant strains were cultured in Fe-replete and Fe-limited media and their total outer membrane proteins were isolated. SDS-PAGE analysis of the outer membrane protein profiles demonstrated that fur:kanP mutant shared a major protein band (Figure 6) with wild type cells grown in Fe-limited media irrespective of the concentration of iron in the medium. This band contained several TonB-dependent OM Fe3+-siderophore receptors [13,14]. This result is consistent with the model in which the TonB-dependent receptors with putative roles in iron uptake are regulated by fur [6].

Bottom Line: Unlike the wild type, the fur:kanP mutant was capable of utilizing iron-bound ferrioxamine without any lag phase and showed over expression of several outer membrane TonB-dependent receptor proteins irrespective of Fe availability.Our studies have clearly indicated a role in Fe regulation by the Fur protein encoded by N. europaea NE0616 gene.Additional studies are required to fully delineate role of this fur homolog.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Botany and Plant Pathology, 2082 Cordley, Oregon State University, Corvallis, OR 97331, USA.

ABSTRACT

Background: In response to environmental iron concentrations, many bacteria coordinately regulate transcription of genes involved in iron acquisition via the ferric uptake regulation (Fur) system. The genome of Nitrosomonas europaea, an ammonia-oxidizing bacterium, carries three genes (NE0616, NE0730 and NE1722) encoding proteins belonging to Fur family.

Results: Of the three N. europaea fur homologs, only the Fur homolog encoded by gene NE0616 complemented the Escherichia coli H1780 fur mutant. A N. europaea fur:kanP mutant strain was created by insertion of kanamycin-resistance cassette in the promoter region of NE0616 fur homolog. The total cellular iron contents of the fur:kanP mutant strain increased by 1.5-fold compared to wild type when grown in Fe-replete media. Relative to the wild type, the fur:kanP mutant exhibited increased sensitivity to iron at or above 500 μM concentrations. Unlike the wild type, the fur:kanP mutant was capable of utilizing iron-bound ferrioxamine without any lag phase and showed over expression of several outer membrane TonB-dependent receptor proteins irrespective of Fe availability.

Conclusions: Our studies have clearly indicated a role in Fe regulation by the Fur protein encoded by N. europaea NE0616 gene. Additional studies are required to fully delineate role of this fur homolog.

Show MeSH
Related in: MedlinePlus