How Does the DraG–P
            <sub>II</sub>
            Complex Regulate Nitrogenase Activity in Azospirillum brasilense?

Li, Xiao Dan; Winkler, Fritz K.; Huergo, Luciano F.

doi:10.1002/9781119053095.ch13

Cited by 1 publication

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References 28 publications

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“…In contrast to all known structures of PII proteins complexed to their targets, the interaction of DraG with GlnZ does not require the GlnZ T‐loop. Although the GlnZ T‐loop is highly flexible and could not be modeled in the previously determined DraG‐GlnZ crystal structure , the interaction with DraG is expected to restrict the mobility of the T‐loop, as more conformations will be forbidden within the DraG‐GlnZ . This mode of interaction allows DraG and GlnZ to form a complex with AmtB, in which the GlnZ T‐loops participate and become ordered, by analogy with the AmtB‐GlnK complex .…”

Section: Resultsmentioning

confidence: 99%

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The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense

et al. 2019

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The ammonium‐dependent posttranslational regulation of nitrogenase activity in Azospirillum brasilense requires dinitrogenase reductase ADP‐ribosyl transferase (DraT) and dinitrogenase reductase ADP‐glycohydrolase (DraG). These enzymes are reciprocally regulated by interaction with the PII proteins, GlnB and GlnZ. In this study, purified ADP‐ribosylated Fe‐protein was used as substrate to study the mechanism involved in the regulation of A. brasilense DraG in vitro. The data show that DraG is partially inhibited by GlnZ and that DraG inhibition is further enhanced by the simultaneous presence of GlnZ and AmtB. These results are the first to demonstrate experimentally that DraG inactivation requires the formation of a ternary DraG‐GlnZ‐AmtB complex in vitro. Previous structural data have revealed that when the DraG‐GlnZ complex associates with AmtB, the flexible T‐loops of the trimeric GlnZ bind to AmtB and become rigid; these molecular events stabilize the DraG‐GlnZ complex, resulting in DraG inactivation. To determine whether restraining the flexibility of the GlnZ T‐loops is a limiting factor in DraG inhibition, we used a GlnZ variant that carries a partial deletion of the T‐loop (GlnZΔ42‐54). However, although the GlnZΔ42‐54 variant was more effective in inhibiting DraG in vitro, it bound to DraG with a slightly lower affinity than does wild‐type GlnZ and was not competent to completely inhibit DraG activity either in vitro or in vivo. We, therefore, conclude that the formation of a ternary complex between DraG‐GlnZ‐AmtB is necessary for the inactivation of DraG.

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Section: Resultsmentioning

confidence: 99%

“…Our current hypothesis is that the DraG-GlnZ complex is not stable enough in vivo to effectively inhibit DraG. The further engagement of AmtB to form a ternary DraG-GlnZ-AmtB complex would be required to enhance the apparent affinity of the DraG-GlnZ interaction thereby allowing effective inhibition of DraG [17,18,20].…”

Section: Discussionmentioning

confidence: 99%

The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense

et al. 2019

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How Does the DraG–P _II Complex Regulate Nitrogenase Activity in Azospirillum brasilense?

Cited by 1 publication

References 28 publications

The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense

The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense

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How Does the DraG–P II Complex Regulate Nitrogenase Activity in Azospirillum brasilense?

Cited by 1 publication

References 28 publications

The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense

The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense

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How Does the DraG–P _II Complex Regulate Nitrogenase Activity in Azospirillum brasilense?