Two Menkes-type ATPases Supply Copper for Photosynthesis inSynechocystis PCC 6803

Abstract

Synechocystis PCC 6803 contains four genes encoding polypeptides with sequence features of CPx-type ATPases, two of which are now designated pacS and ctaA. We show that CtaA and PacS (but not the related transporters, ZiaA or CoaT) facilitate switching to the use of copper (in plastocyanin) as an alternative to iron (in cytochrome c 6 ) for the carriage of electrons within the thylakoid lumen. Disruption of pacS reduced copper tolerance but enhanced silver tolerance, and pacS-mediated restoration of copper tolerance was used to select transformants. Disruption of ctaA caused no change in copper tolerance but reduced the amount of copper cell ؊1 . In cultures supplemented with 0.2 M copper, photooxidation of cytochrome c 6 (PetJ) was depressed in wild-type cells but remained elevated in both Synechocystis PCC 6803(ctaA) and Synechocystis PCC 6803(pacS). Conversely, plastocyanin transcripts (petE) were less abundant in both mutants at this [copper]. Synechocystis PCC 6803(ctaA) and Synechocystis PCC 6803(pacS) showed increased iron dependence with impaired growth in deferoxamine mesylate (iron chelator)-containing media. Double mutants also deficient in cytochrome c 6 , Synechocystis PCC 6803(petJ,ctaA) and Synechocystis PCC 6803(petJ,pacS), were viable, but the former had increased copper dependence with severely impaired growth in the presence of bathocuproinedisulfonic acid (copper chelator). Analogous transporters are likely to supply copper to plastocyanin in chloroplasts.

Functional and Biochemical Characterization of Cucumber Genes Encoding Two Copper ATPases CsHMA5.1 and CsHMA5.2

“…Similarly, AtHMA5, AtHMA6/PAA1, and OsHMA5 have been shown to participate in intracellular copper sequestration when expressed in the ⌬ccc2 yeast strain, lacking the Golgi-resident endogenous copper Cu ϩ /Ag ϩ -ATPase Ccc2p (12,18,45). According to available data, P 1B1 -ATPases participate in the maintenance of copper homeostasis either through the import of copper into the cell (PCC7942 and PCC6803 in cyanobacteria Synechococcus and Synechocystis, respectively) and intracellular compartments to supply copper to copper-dependent enzymes (ATP7A, ATP7B, Ccc2p, AtHMA6/PAA1, AtHMA8/PAA2, and AtHMA7/RAN1) or through the active efflux of copper out of the cell (CopA, OsHMA5) (12,18,56,57). In addition, our study provides the first evidence for the involvement of P 1B1 -ATPases in the active influx of copper into vacuoles.…”

Bacterial outer membrane channel for divalent metal ion acquisition

“…Nutritional metals, such as manganese, copper, cobalt, and zinc are available as the divalent cation in aerobic environments, and are thus soluble. Whereas cytoplasmic (inner) membrane transporters of free metal ions are well characterized in bacteria (9)(10)(11)(12), translocation across the outer membrane and into the periplasm has not been described. In principle, outer membrane pores with no or low selectivity should readily accommodate the diffusion of these small, soluble nutrients that are needed only in low quantities (4,5).…”

Mutagenesis of a Copper P-Type ATPase Encoding Genein Methylococcus capsulatus (Bath) Results inCopper-Resistance

“…hirae CopB [2], E. coli CopA, Synechococcus elongates PacS and Synechococcus sp. CtaA [20] were retrieved via the National Center for Biotechnology Information (NCBI) website (http://www.ncbi.nlm.nih.gov/). Sequences were aligned using PRALINEPSI strategy of the freely available PRALINE http://www.ibi.vu.nl/programs/pralinewww/ [21].…”

“…coli CopA, Synechococcus elongates PacS and Synechococcus sp. CtaA [20] ranged from 37 -46%. Furthermore, eight membrane-spanning helices were predicted in M. capsulatus CopA.…”

“…In support of that, Ent. hirae CopB which did not confer silver resistance to cells, could transport copper and silver in vivo with similar rate [2], [20] . This is also indicated that some P-type ATPases share substrate specificity for copper and silver due to chemical similarities between these metals [5] ΔcopA1 mutant accumulated only half the copper concentration of the wild-type.…”