2MM0

Solution Structures of active Ptr ToxB and its inactive homolog highlight protein dynamics as a modulator of toxin activity

2MM0 の概要

• エントリーDOI: 10.2210/pdb2mm0/pdb
• NMR情報: BMRB: 19840
• 分子名称: Host-selective toxin protein (1 entity in total)
• 機能のキーワード: toxin
• 由来する生物種: Pyrenophora tritici-repentis
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 6546.41

構造登録者

Nyarko, A.,Singarapu, K.,Figueroa, M.,Manning, V.,Pandelova, I.,Wolpert, T.,Ciuffetti, L.,Barbar, E. (登録日: 2014-03-06, 公開日: 2014-08-06, 最終更新日: 2023-06-14)

主引用文献

Nyarko, A.,Singarapu, K.K.,Figueroa, M.,Manning, V.A.,Pandelova, I.,Wolpert, T.J.,Ciuffetti, L.M.,Barbar, E.
Solution NMR Structures of Pyrenophora tritici-repentis ToxB and Its Inactive Homolog Reveal Potential Determinants of Toxin Activity.
J.Biol.Chem., 289:25946-25956, 2014

PubMed Abstract: Pyrenophora tritici-repentis Ptr ToxB (ToxB) is a proteinaceous host-selective toxin produced by Pyrenophora tritici-repentis (P. tritici-repentis), a plant pathogenic fungus that causes the disease tan spot of wheat. One feature that distinguishes ToxB from other host-selective toxins is that it has naturally occurring homologs in non-pathogenic P. tritici-repentis isolates that lack toxic activity. There are no high-resolution structures for any of the ToxB homologs, or for any protein with >30% sequence identity, and therefore what underlies activity remains an open question. Here, we present the NMR structures of ToxB and its inactive homolog Ptr toxb. Both proteins adopt a β-sandwich fold comprising three strands in each half that are bridged together by two disulfide bonds. The inactive toxb, however, shows higher flexibility localized to the sequence-divergent β-sandwich half. The absence of toxic activity is attributed to a more open structure in the vicinity of one disulfide bond, higher flexibility, and residue differences in an exposed loop that likely impacts interaction with putative targets. We propose that activity is regulated by perturbations in a putative active site loop and changes in dynamics distant from the site of activity. Interestingly, the new structures identify AvrPiz-t, a secreted avirulence protein produced by the rice blast fungus, as a structural homolog to ToxB. This homology suggests that fungal proteins involved in either disease susceptibility such as ToxB or resistance such as AvrPiz-t may have a common evolutionary origin.

PubMed: 25063993
DOI: 10.1074/jbc.M114.569103

実験手法

SOLUTION NMR