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Functional Characterization of the FNT Family Nitrite Transporter of Marine Picocyanobacteria.

Maeda S, Murakami A, Ito H, Tanaka A, Omata T - Life (Basel) (2015)

Bottom Line: A strongly conserved hydrophilic amino acid sequence was found at the C-termini of the deduced NitM sequences from α-cyanobacteria, with a notable exception of the Synechococcus sp. strain CC9605 NitM protein, which entirely lacked the C-terminal amino acids.The C-terminal sequence was not conserved in the NitM proteins from β-cyanobacteria carrying the Type 1b RuBisCO, including the one from Synechococcus sp. strain PCC7002.Expression of the truncated nitM genes from Synechococcus sp. strain CC9311 and Prochlorococcus marinus strain MIT9313, encoding the proteins lacking the conserved C-terminal region, conferred nitrite uptake activity on the NA4 mutant, indicating that the C-terminal region of α-cyanobacterial NitM proteins inhibits the activity of the transporter.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. maeda@agr.nagoya-u.ac.jp.

ABSTRACT
Many of the cyanobacterial species found in marine and saline environments have a gene encoding a putative nitrite transporter of the formate/nitrite transporter (FNT) family. The presumed function of the gene (designated nitM) was confirmed by functional expression of the gene from the coastal marine species Synechococcus sp. strain PCC7002 in the nitrite-transport-less mutant (NA4) of the freshwater cyanobacterium Synechococcus elongatus strain PCC7942. The NitM-mediated nitrite uptake showed an apparent Km (NO2-) of about 8 μM and was not inhibited by nitrate, cyanate or formate. Of the nitM orthologs from the three oceanic cyanobacterial species, which are classified as α-cyanobacteria on the basis of the occurrence of Type 1a RuBisCO, the one from Synechococcus sp. strain CC9605 conferred nitrite uptake activity on NA4, but those from Synechococcus sp. strain CC9311 and Prochlorococcus marinus strain MIT9313 did not. A strongly conserved hydrophilic amino acid sequence was found at the C-termini of the deduced NitM sequences from α-cyanobacteria, with a notable exception of the Synechococcus sp. strain CC9605 NitM protein, which entirely lacked the C-terminal amino acids. The C-terminal sequence was not conserved in the NitM proteins from β-cyanobacteria carrying the Type 1b RuBisCO, including the one from Synechococcus sp. strain PCC7002. Expression of the truncated nitM genes from Synechococcus sp. strain CC9311 and Prochlorococcus marinus strain MIT9313, encoding the proteins lacking the conserved C-terminal region, conferred nitrite uptake activity on the NA4 mutant, indicating that the C-terminal region of α-cyanobacterial NitM proteins inhibits the activity of the transporter.

No MeSH data available.


Related in: MedlinePlus

Phylogenetic tree of the NitM proteins of cyanobacteria. The NAR1.1 protein of the green algae Chlamydomonas reinhardtii was added as outgroup. Phylogenies are based on protein sequences that were aligned using the program ClustalX. A phylogenetic tree was created using the UPGMA (Unweighted Pair Group Method with Arithmetic mean) clustering method of ClustalX. The abbreviations for the species names are as follows. Cre, Chlamydomonas reinhardtii; Csp, Cyanobium sp.; CSs, Candidatus Synechococcus spongiarum; Cst, Cyanobacterium stanieri; Dsa, Dactylococcopsis salina; fcy, filamentous cyanobacterium; Gsp, Geitlerinema sp.; Hsp, Halothece sp.; Pma, Prochlorococcus marinus; Ssp, Synechococcus sp.
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life-05-00432-f001: Phylogenetic tree of the NitM proteins of cyanobacteria. The NAR1.1 protein of the green algae Chlamydomonas reinhardtii was added as outgroup. Phylogenies are based on protein sequences that were aligned using the program ClustalX. A phylogenetic tree was created using the UPGMA (Unweighted Pair Group Method with Arithmetic mean) clustering method of ClustalX. The abbreviations for the species names are as follows. Cre, Chlamydomonas reinhardtii; Csp, Cyanobium sp.; CSs, Candidatus Synechococcus spongiarum; Cst, Cyanobacterium stanieri; Dsa, Dactylococcopsis salina; fcy, filamentous cyanobacterium; Gsp, Geitlerinema sp.; Hsp, Halothece sp.; Pma, Prochlorococcus marinus; Ssp, Synechococcus sp.

Mentions: As of September 2014, there are 72 completely sequenced cyanobacterial genomes available in GenBank, 21 of which are from α-cyanobacteria and the other 51 genomes are from β-cyanobacteria (Supplementary Table S1). Among the α-cyanobacterial strains, seven strains have the capacity of nitrate assimilation and eleven have the capacity of nitrite assimilation, with nine of the eleven strains carrying the gene for the putative nitrite transporter of the FNT family. The gene is closely linked to the nitrite reductase gene nirA in α-cyanobacteria, suggesting that the gene is associated with the capacity for nitrite assimilation. Unlike α-cyanobacteria, β-cyanobacteria are generally capable of assimilation of nitrate and nitrite, but only four out of the 51 β-cyanobacteria were found to have the gene encoding the FNT family proteins. These include the coastal marine strain Synechococcus sp. strain PCC 7002 and the two halotolerant strains Dactylococcopsis salina strain PCC 8305 and Halothece sp. strain PCC 7418. It thus appeared that the FNT family protein is related to nitrite utilization in marine and saline environments. Phylogenetic analysis of all of the FNT family proteins available in GenBank show that the proteins from α-cyanobacteria and β-cyanobacteria form distinct groups (Figure 1).


Functional Characterization of the FNT Family Nitrite Transporter of Marine Picocyanobacteria.

Maeda S, Murakami A, Ito H, Tanaka A, Omata T - Life (Basel) (2015)

Phylogenetic tree of the NitM proteins of cyanobacteria. The NAR1.1 protein of the green algae Chlamydomonas reinhardtii was added as outgroup. Phylogenies are based on protein sequences that were aligned using the program ClustalX. A phylogenetic tree was created using the UPGMA (Unweighted Pair Group Method with Arithmetic mean) clustering method of ClustalX. The abbreviations for the species names are as follows. Cre, Chlamydomonas reinhardtii; Csp, Cyanobium sp.; CSs, Candidatus Synechococcus spongiarum; Cst, Cyanobacterium stanieri; Dsa, Dactylococcopsis salina; fcy, filamentous cyanobacterium; Gsp, Geitlerinema sp.; Hsp, Halothece sp.; Pma, Prochlorococcus marinus; Ssp, Synechococcus sp.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4390861&req=5

life-05-00432-f001: Phylogenetic tree of the NitM proteins of cyanobacteria. The NAR1.1 protein of the green algae Chlamydomonas reinhardtii was added as outgroup. Phylogenies are based on protein sequences that were aligned using the program ClustalX. A phylogenetic tree was created using the UPGMA (Unweighted Pair Group Method with Arithmetic mean) clustering method of ClustalX. The abbreviations for the species names are as follows. Cre, Chlamydomonas reinhardtii; Csp, Cyanobium sp.; CSs, Candidatus Synechococcus spongiarum; Cst, Cyanobacterium stanieri; Dsa, Dactylococcopsis salina; fcy, filamentous cyanobacterium; Gsp, Geitlerinema sp.; Hsp, Halothece sp.; Pma, Prochlorococcus marinus; Ssp, Synechococcus sp.
Mentions: As of September 2014, there are 72 completely sequenced cyanobacterial genomes available in GenBank, 21 of which are from α-cyanobacteria and the other 51 genomes are from β-cyanobacteria (Supplementary Table S1). Among the α-cyanobacterial strains, seven strains have the capacity of nitrate assimilation and eleven have the capacity of nitrite assimilation, with nine of the eleven strains carrying the gene for the putative nitrite transporter of the FNT family. The gene is closely linked to the nitrite reductase gene nirA in α-cyanobacteria, suggesting that the gene is associated with the capacity for nitrite assimilation. Unlike α-cyanobacteria, β-cyanobacteria are generally capable of assimilation of nitrate and nitrite, but only four out of the 51 β-cyanobacteria were found to have the gene encoding the FNT family proteins. These include the coastal marine strain Synechococcus sp. strain PCC 7002 and the two halotolerant strains Dactylococcopsis salina strain PCC 8305 and Halothece sp. strain PCC 7418. It thus appeared that the FNT family protein is related to nitrite utilization in marine and saline environments. Phylogenetic analysis of all of the FNT family proteins available in GenBank show that the proteins from α-cyanobacteria and β-cyanobacteria form distinct groups (Figure 1).

Bottom Line: A strongly conserved hydrophilic amino acid sequence was found at the C-termini of the deduced NitM sequences from α-cyanobacteria, with a notable exception of the Synechococcus sp. strain CC9605 NitM protein, which entirely lacked the C-terminal amino acids.The C-terminal sequence was not conserved in the NitM proteins from β-cyanobacteria carrying the Type 1b RuBisCO, including the one from Synechococcus sp. strain PCC7002.Expression of the truncated nitM genes from Synechococcus sp. strain CC9311 and Prochlorococcus marinus strain MIT9313, encoding the proteins lacking the conserved C-terminal region, conferred nitrite uptake activity on the NA4 mutant, indicating that the C-terminal region of α-cyanobacterial NitM proteins inhibits the activity of the transporter.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. maeda@agr.nagoya-u.ac.jp.

ABSTRACT
Many of the cyanobacterial species found in marine and saline environments have a gene encoding a putative nitrite transporter of the formate/nitrite transporter (FNT) family. The presumed function of the gene (designated nitM) was confirmed by functional expression of the gene from the coastal marine species Synechococcus sp. strain PCC7002 in the nitrite-transport-less mutant (NA4) of the freshwater cyanobacterium Synechococcus elongatus strain PCC7942. The NitM-mediated nitrite uptake showed an apparent Km (NO2-) of about 8 μM and was not inhibited by nitrate, cyanate or formate. Of the nitM orthologs from the three oceanic cyanobacterial species, which are classified as α-cyanobacteria on the basis of the occurrence of Type 1a RuBisCO, the one from Synechococcus sp. strain CC9605 conferred nitrite uptake activity on NA4, but those from Synechococcus sp. strain CC9311 and Prochlorococcus marinus strain MIT9313 did not. A strongly conserved hydrophilic amino acid sequence was found at the C-termini of the deduced NitM sequences from α-cyanobacteria, with a notable exception of the Synechococcus sp. strain CC9605 NitM protein, which entirely lacked the C-terminal amino acids. The C-terminal sequence was not conserved in the NitM proteins from β-cyanobacteria carrying the Type 1b RuBisCO, including the one from Synechococcus sp. strain PCC7002. Expression of the truncated nitM genes from Synechococcus sp. strain CC9311 and Prochlorococcus marinus strain MIT9313, encoding the proteins lacking the conserved C-terminal region, conferred nitrite uptake activity on the NA4 mutant, indicating that the C-terminal region of α-cyanobacterial NitM proteins inhibits the activity of the transporter.

No MeSH data available.


Related in: MedlinePlus