4X0E

Structure of M. tuberculosis nicotinate mono nucleotide adenylyltransferase

4X0E の概要

• エントリーDOI: 10.2210/pdb4x0e/pdb
• 分子名称: Probable nicotinate-nucleotide adenylyltransferase, SULFATE ION, 2-(N-MORPHOLINO)-ETHANESULFONIC ACID, ... (4 entities in total)
• 機能のキーワード: enzyme inhibitors, transferase
• 由来する生物種: Mycobacterium tuberculosis
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 48263.48

構造登録者

Zuccola, H.J.,Ostermna, A.L. (登録日: 2014-11-21, 公開日: 2015-01-28, 最終更新日: 2024-02-28)

主引用文献

Rodionova, I.A.,Zuccola, H.J.,Sorci, L.,Aleshin, A.E.,Kazanov, M.D.,Ma, C.T.,Sergienko, E.,Rubin, E.J.,Locher, C.P.,Osterman, A.L.
Mycobacterial nicotinate mononucleotide adenylyltransferase: structure, mechanism, and implications for drug discovery.
J. Biol. Chem., 290:7693-7706, 2015

PubMed Abstract: Nicotinate mononucleotide adenylyltransferase NadD is an essential enzyme in the biosynthesis of the NAD cofactor, which has been implicated as a target for developing new antimycobacterial therapies. Here we report the crystal structure of Mycobacterium tuberculosis NadD (MtNadD) at a resolution of 2.4 Å. A remarkable new feature of the MtNadD structure, compared with other members of this enzyme family, is a 310 helix that locks the active site in an over-closed conformation. As a result, MtNadD is rendered inactive as it is topologically incompatible with substrate binding and catalysis. Directed mutagenesis was also used to further dissect the structural elements that contribute to the interactions of the two MtNadD substrates, i.e. ATP and nicotinic acid mononucleotide (NaMN). For inhibitory profiling of partially active mutants and wild type MtNadD, we used a small molecule inhibitor of MtNadD with moderate affinity (Ki ∼ 25 μM) and antimycobacterial activity (MIC80) ∼ 40-80 μM). This analysis revealed interferences with some of the residues in the NaMN binding subsite consistent with the competitive inhibition observed for the NaMN substrate (but not ATP). A detailed steady-state kinetic analysis of MtNadD suggests that ATP must first bind to allow efficient NaMN binding and catalysis. This sequential mechanism is consistent with the requirement of transition to catalytically competent (open) conformation hypothesized from structural modeling. A possible physiological significance of this mechanism is to enable the down-regulation of NAD synthesis under ATP-limiting dormancy conditions. These findings point to a possible new strategy for designing inhibitors that lock the enzyme in the inactive over-closed conformation.

PubMed: 25631047
DOI: 10.1074/jbc.M114.628016

実験手法

X-RAY DIFFRACTION (2.41 Å)