Two Plant Bacteria, S. meliloti and Ca. Liberibacter asiaticus, Share Functional znuABC Homologues That Encode for a High Affinity Zinc Uptake System

• Published in: PloS one 2012-05, Vol.7 (5), p.e37340-e37340
• Main Authors: Vahling-Armstrong, Cheryl M, Zhou, Huasong, Benyon, Lesley, Morgan, J. Kent, Duan, Yongping, Yang, Ching-Hong
• Format: Article
• Language: English
• Subjects: Agriculture; Amino Acid Sequence; Antibiotics; ATP-Binding Cassette Transporters - chemistry; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Bacteria; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biology; Campylobacter; Candidatus Liberibacter asiaticus; Citrus; Citrus - microbiology; Citrus fruits; Cluster analysis; Complementation; Diaphorina citri; E coli; Edetic Acid - metabolism; endosymbionts; Ensifer meliloti; Escherichia coli; Escherichia coli - chemistry; Escherichia coli - genetics; Escherichia coli - growth & development; Escherichia coli - metabolism; Flowers & plants; Gene clusters; Gene expression; Genes; Genes, Bacterial; Genomes; Homology; Horticulture; Laboratories; Listeria; Molecular Sequence Data; Multigene Family; Nitrogen; Pathogenesis; pathogens; physiological transport; Plant pathology; Plants - microbiology; Proteins; Rhizobiaceae; Rhizobiaceae - chemistry; Rhizobiaceae - genetics; Rhizobiaceae - growth & development; Rhizobiaceae - metabolism; Sequence Alignment; Sinorhizobium meliloti; Sinorhizobium meliloti - chemistry; Sinorhizobium meliloti - genetics; Sinorhizobium meliloti - growth & development; Sinorhizobium meliloti - metabolism; Streptococcus infections; Urinary tract diseases; Urinary tract infections; Urogenital system; Zinc; Zinc - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0037340

The Znu system, encoded for by znuABC , can be found in multiple genera of bacteria and has been shown to be responsible for the import of zinc under low zinc conditions. Although this high-affinity uptake system is known to be important for both growth and/or pathogenesis in bacteria, it has not been functionally characterized in a plant-associated bacterium. A single homologue of this system has been identified in the plant endosymbiont, Sinorhizobium meliloti , while two homologous systems were found in the destructive citrus pathogen, Candidatus Liberibacter asiaticus. To understand the role of these protein homologues, a complementation assay was devised allowing the individual genes that comprise the system to be assayed independently for their ability to reinstate a partially-inactivated Znu system. Results from the assays have demonstrated that although all of the genes from S. meliloti were able to restore activity, only one of the two Ca. Liberibacter asiaticus encoded gene clusters contained genes that were able to functionally complement the system. Additional analysis of the gene clusters reveals that distinct modes of regulation may also exist between the Ca. Liberibacter asiaticus and S. meliloti import systems despite the intracellular-plant niche common to both of these bacteria.