Control of
            <i>Herbaspirillum seropedicae</i>
            NifA Activity by Ammonium Ions and Oxygen

Souza, Emanuel Maltempi de; Pedrosa, F. O.; Drummond, Martin; Rigo, L. U.; Yates, M. G.

doi:10.1128/jb.181.2.681-684.1999

Cited by 75 publications

(54 citation statements)

References 28 publications

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“…On the other hand, nifH expression was not inhibited by ammonia. This result also agrees with the previous observation [23] that the N-terminal domain of H. seropedicae NifA is involved in ammonia-sensing. The N-terminal domain of the NifA protein may interact with a nitrogen-sensing protein or signal molecule which, in turn, controls the interaction between the central domain and the RNA polymerase.…”

Section: Resultssupporting

confidence: 93%

“…SDS-PAGE analysis con¢rmed the expression of the proteins in all conditions tested (not shown). Promoter activation as revealed by L-galactosidase activity was detected only when cells were induced under a nitrogen gas phase, con¢rming the oxygen-sensitivity of H. seropedicae NifA [23]. These results are also consistent with the hypothesis that the oxygen-sensitivity does not involve the N-terminal domain of NifA but rather the central domain and the ID linker, probably involving the putative metal-binding and redox status-sensing cysteine motif, Cys-X II -Cys-X IW -Cys-X R -Cys [6].…”

Section: Resultsmentioning

confidence: 76%

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Expression and functional analysis of an N‐truncated NifA protein of Herbaspirillum seropedicae

et al. 1999

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In Herbaspirillum seropedicae, an endophytic diazotroph, nif gene expression is under the control of the transcriptional activator NifA. We have over-expressed and purified a protein containing the central and C-terminal domains of the H. seropedicae NifA protein, N-truncated NifA, fused to a His-Tag sequence. This fusion protein was found to be partially soluble and was purified by affinity chromatography. Band shift and footprinting assays showed that the N-truncated NifA protein was able to bind specifically to the H. seropedicae nifB promoter region. In vivo analysis showed that this protein activated the nifH promoter of Klebsiella pneumoniae in Escherichia coli only in the absence of oxygen and this activation was not negatively controlled by ammonium ions.z 1999 Federation of European Biochemical Societies.

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 76%

Expression and functional analysis of an N‐truncated NifA protein of Herbaspirillum seropedicae

et al. 1999

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“…Hence, the interaction of the N-terminal domain of H. seropedicae is speci¢c inasmuch that did not interfere with the ATPase activity of the homologous NtrC, but the A. vinelandii NifA protein has su¤cient similarity (42%) to allow negative interaction. The observation that the N-terminal domain negatively controls the NifA activity is in agreement with previous in vivo results showing that when the N-terminal domain was expressed at a higher level, the N-truncated NifA was transcriptionally inactive [19] and that may also explain why the full length form of NifA was inactive in E. coli [13].…”

Section: Resultssupporting

confidence: 92%

“…2A). This is in agreement with in vivo data, which indicated that the H. seropedicae protein is thermostable [13]. The ATPase activity of the N-truncated protein was stimulated by the addition of the H. seropedicae nifB promoter (Fig.…”

Section: Resultssupporting

confidence: 91%

Inter‐domain cross‐talk controls the NifA protein activity of Herbaspirillum seropedicae

et al. 2001

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Herbaspirillum seropedicae is an endophytic diazotroph, which colonizes sugar cane, wheat, rice and maize. The activity of NifA, a transcriptional activator of nif genes in H. seropedicae, is controlled by ammonium ions through a mechanism involving its N-terminal domain. Here we show that this domain interacts specifically in vitro with the N-truncated NifA protein, as revealed by protection against proteolysis, and this interaction caused an inhibitory effect on both the ATPase and DNA-binding activities of the N-truncated NifA protein. We suggest that the N-terminal domain inhibits NifA-dependent transcriptional activation by an inter-domain cross-talk between the catalytic domain of the NifA protein and its regulatory N-terminal domain in response to fixed nitrogen. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

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“…The mechanism involved in this control is not known. Souza et al [30] observed that the activity of a H. seropedicae N-terminal domain-truncated NifA (DNTD) was independent of ammonium levels, suggesting that the N-terminal domain (NTD) plays a role in the control of NifA activity by ammonium. Arsene et al [3] made a similar observation in A. brasilense and suggested that PII-UMP may interact with the NTD of NifA to change its activity.…”

mentioning

confidence: 99%

Herbaspirillum seropedicae signal transduction protein PII is structurally similar to the enteric GlnK

Benelli

Buck

Polikarpov

et al. 2002

European Journal of Biochemistry

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PII-like proteins are signal transduction proteins found in bacteria, archaea and eukaryotes. They mediate a variety of cellular responses. A second PII-like protein, called GlnK, has been found in several organisms. In the diazotroph Herbaspirillum seropedicae, PII protein is involved in sensing nitrogen levels and controlling nitrogen fixation genes. In this work, the crystal structure of the unliganded H. seropedicae PII was solved by X-ray diffraction. H. seropedicae PII has a Gly residue, Gly108 preceding Pro109 and the main-chain forms a b turn. The glycine at position 108 allows a bend in the C-terminal main-chain, thereby modifying the surface of the cleft between monomers and potentially changing function. The structure suggests that the C-terminal region of PII proteins may be involved in specificity of function, and nonenteric diazotrophs are found to have the C-terminal consensus XGXDAX(107-112). We are also proposing binding sites for ATP and 2-oxoglutarate based on the structural alignment of PII with PII-ATP/ GlnK-ATP, 5-carboxymethyl-2-hydroxymuconate isomerase and 4-oxalocrotonate tautomerase bound to the inhibitor 2-oxo-3-pentynoate.

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Control of Herbaspirillum seropedicae NifA Activity by Ammonium Ions and Oxygen

Cited by 75 publications

References 28 publications

Expression and functional analysis of an N‐truncated NifA protein of Herbaspirillum seropedicae

Expression and functional analysis of an N‐truncated NifA protein of Herbaspirillum seropedicae

Inter‐domain cross‐talk controls the NifA protein activity of Herbaspirillum seropedicae

Herbaspirillum seropedicae signal transduction protein PII is structurally similar to the enteric GlnK

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