Purification of two putative type II NADH dehydrogenases with different substrate specificities from alkaliphilic Bacillus pseudofirmus OF4
A putative Type II NADH dehydrogenase from Halobacillus dabanensis was recently reported to have Na +/H + antiport activity (and called Nap), raising the possibility of direct coupling of respiration to antiport-dependent pH homeostasis. This study characterized a homologous type II NADH dehydrogena...
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Published in | Biochimica et biophysica acta Vol. 1777; no. 5; pp. 453 - 461 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
Elsevier B.V
01.05.2008
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Subjects | |
Online Access | Get full text |
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Summary: | A putative Type II NADH dehydrogenase from
Halobacillus dabanensis was recently reported to have Na
+/H
+ antiport activity (and called Nap), raising the possibility of direct coupling of respiration to antiport-dependent pH homeostasis. This study characterized a homologous type II NADH dehydrogenase of genetically tractable alkaliphilic
Bacillus pseudofirmus OF4, in which evidence supports antiport-based pH homeostasis that is mediated entirely by secondary antiport. Two candidate type II NADH dehydrogenase genes with canonical GXGXXG motifs were identified in a draft genome sequence of
B. pseudofirmus OF4. The gene product designated NDH-2A exhibited homology to enzymes from
Bacillus subtilis and
Escherichia coli whereas NDH-2B exhibited homology to the
H. dabanensis Nap protein and its alkaliphilic
Bacillus halodurans C-125 homologue. The
ndh-2A, but not the
ndh-2B, gene complemented the growth defect of an NADH dehydrogenase-deficient
E. coli mutant. Neither gene conferred Na
+-resistance on an antiporter-deficient
E. coli strain, nor did they confer Na
+/H
+ antiport activity in vesicle assays. The purified hexa-histidine-tagged gene products were approximately 50 kDa, contained noncovalently bound FAD and oxidized NADH. They were predominantly cytoplasmic in
E. coli, consonant with the absence of antiport activity. The catalytic properties of NDH-2A were more consistent with a major respiratory role than those of NDH-2B. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0005-2728 0006-3002 1879-2650 |
DOI: | 10.1016/j.bbabio.2008.02.004 |