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Fuchsman CA, Carlson MCG, Garcia Prieto D, Hays MD, Rocap G. Cyanophage host-derived genes reflect contrasting selective pressures with depth in the oxic and anoxic water column of the Eastern Tropical North Pacific. Environ Microbiol 2020; 23:2782-2800. [PMID: 32869473 DOI: 10.1111/1462-2920.15219] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 08/14/2020] [Accepted: 08/27/2020] [Indexed: 01/19/2023]
Abstract
Cyanophages encode host-derived genes that may increase their fitness. We examined the relative abundance of 18 host-derived cyanophages genes in metagenomes and viromes along depth profiles from the Eastern Tropical North Pacific Oxygen Deficient Zone (ETNP ODZ) where Prochlorococcus dominates a secondary chlorophyll maximum within the ODZ. Cyanophages at the oxic primary chlorophyll maximum encoded genes related to light and phosphate stress (psbA, psbD and pstS in T4-like and psbA in T7-like), but the proportion of cyanophage with these genes decreased with depth. The proportion of cyanophage with purine biosynthesis genes increased with depth in T4-like, but not T7-like cyanophages. No additional host-derived genes were found in deep T7-like cyanophages, suggesting that T4-like and T7-like cyanophages have different host-derived gene acquisition strategies, possibly linked to their different genome packaging mechanisms. In contrast to the ETNP, in the oxic North Atlantic T4-like cyanophages encoded psbA and pstS throughout the euphotic zone. Differences in pstS between the ETNP and the North Atlantic stations were consistent with differences in phosphate concentrations in those regimes. We suggest that the low proportion of cyanophage with psbA within the ODZ reflects the stably stratified low-light conditions occupied by their hosts, a Prochlorococcus ecotype endemic to ODZs.
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Affiliation(s)
- Clara A Fuchsman
- School of Oceanography, University of Washington, Seattle, WA, USA.,Horn Point Laboratory, University of Maryland Center of Environmental Science, Cambridge, MD, 21613, USA
| | - Michael C G Carlson
- School of Oceanography, University of Washington, Seattle, WA, USA.,Technion-Israel Institute of Technology, Haifa, Israel
| | - David Garcia Prieto
- School of Oceanography, University of Washington, Seattle, WA, USA.,Horn Point Laboratory, University of Maryland Center of Environmental Science, Cambridge, MD, 21613, USA
| | - Matthew D Hays
- Horn Point Laboratory, University of Maryland Center of Environmental Science, Cambridge, MD, 21613, USA
| | - Gabrielle Rocap
- School of Oceanography, University of Washington, Seattle, WA, USA
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Hunter CA, Plymale NI, Smee KM, Sarisky CA. Experimental characterization of two archaeal inosine 5'-monophosphate cyclohydrolases. PLoS One 2019; 14:e0223983. [PMID: 31622427 PMCID: PMC6797443 DOI: 10.1371/journal.pone.0223983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 10/02/2019] [Indexed: 12/04/2022] Open
Abstract
There is variability as to how archaea catalyze the final step of de novo purine biosynthesis to form inosine 5’-monophosphate (IMP) from 5-formamidoimidazole-4-carboxamide ribonucleotide (FAICAR). Although non-archaea almost uniformly use the bifunctional PurH protein, which has an N-terminal IMP cyclohydrolase (PurH2) fused to a C-terminal folate-dependent aminoimidazole-4-carboxamide ribonucleotide (AICAR) formyltransferase (PurH1) domain, a survey of the genomes of archaea reveals use of PurH2 (with or without fusion to PurH1), the “euryarchaeal signature protein” PurO, or an unidentified crenarchaeal IMP cyclohydrolase. In this report, we present the cloning and functional characterization of two representatives of the known IMP cyclohydrolase families. The locus TK0430 in Thermococcus kodakarensis encodes a PurO-type IMP cyclohydrolase with demonstrated activity despite its position in a cluster of apparently redundant biosynthetic genes, the first functional characterization of a PurO from a non-methanogen. Kinetic characterization reveals a Km for FAICAR of 1.56 ± 0.39 μM and a kcat of 0.48 ± 0.04 s-1. The locus AF1811 from Archaeoglobus fulgidus encodes a PurH2-type IMP cyclohydrolase. This Archaeoglobus fulgidus PurH2 has a Km of 7.8 ± 1.8 μM and kcat of 1.32 ± 0.14 s-1, representing the first characterization of an archaeal PurH2 and the first characterization of PurH2 that naturally occurs unfused to an AICAR formyltransferase domain. Each of these two characterized IMP cyclohydrolases converts FAICAR to IMP in vitro, and each cloned gene allows the growth on purine-deficient media of an E. coli purine auxotroph lacking the purH2 gene.
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Affiliation(s)
- Caroline A. Hunter
- Department of Chemistry, Roanoke College, Salem, Virginia, United States of America
| | - Nicholas I. Plymale
- Department of Chemistry, Roanoke College, Salem, Virginia, United States of America
| | - Kevin M. Smee
- Department of Chemistry, Roanoke College, Salem, Virginia, United States of America
| | - Catherine A. Sarisky
- Department of Chemistry, Roanoke College, Salem, Virginia, United States of America
- * E-mail:
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