Raj Rishi, Kumar Abhay, Savithri H S, Singh Pratibha
Department of Botany, School of Life Science, Mahatma Gandhi Central University, Motihari, Bihar 845401 India.
ICAR-National Research Centre on Litchi, Muzaffarpur, Bihar 842 002 India.
3 Biotech. 2025 May;15(5):146. doi: 10.1007/s13205-025-04305-6. Epub 2025 Apr 30.
Groundnut bud necrosis virus (GBNV) is a tripartite negative sense RNA virus that belongs to tospoviridae family. The M RNA encodes non-structural protein-m (NSm), a movement protein in tospoviruses. In this communication, we demonstrate that, GBNV NSm interacts with ATP and GTP. UV crosslinking with [γ-32P] ATP indicates that GBNV NSm forms two distinct complexes with ATP one of them is Mg dependent and the other is Mg independent. It also binds to ATP- and GTP-coupled agarose resin and shows competition with free ATP and GTP but not with UTP and CTP. The NSm-NTP interaction was further validated by intrinsic fluorescence quenching studies. NTPs and dNTPs both could quench the intrinsic fluorescence of NSm. However, maximum quenching of fluorescence occurred in the presence of GTP, followed by ATP, suggesting that it is the preferred ligand. The extent of fluorescence quenching with different concentrations of GTP was used to calculate the binding constant, and it was found to be 3 μM, lower than that reported for other proteins that can bind NTP. This is the first report of the GTP and ATP binding property of NSm from any Tospoviruses. Further, NSm could also hydrolyze GTP. Preliminary sequence analysis suggests the presence of two putative atypical Walker A motif from amino acid sequences 51-58 and 267-274, indicating that this sequence might be involved in NTP binding. This motif is conserved in most of the tospoviruses. NSm from GBNV an Asian clade, localize to ER network and remodels it to vesicles which has been proposed to be involved in movement through plasmodesmata (PD). Therefore, GTP-NSm interaction might be involved in signaling cell to cell trafficking.
花生芽坏死病毒(GBNV)是一种三分体负链RNA病毒,属于番茄斑萎病毒科。M RNA编码非结构蛋白m(NSm),这是番茄斑萎病毒属病毒中的一种运动蛋白。在本通讯中,我们证明GBNV NSm与ATP和GTP相互作用。用[γ-32P]ATP进行紫外交联表明,GBNV NSm与ATP形成两种不同的复合物,其中一种依赖Mg,另一种不依赖Mg。它还与ATP和GTP偶联的琼脂糖树脂结合,并显示出与游离ATP和GTP存在竞争,但与UTP和CTP不存在竞争。通过内在荧光猝灭研究进一步验证了NSm与NTP的相互作用。NTP和dNTP都能猝灭NSm的内在荧光。然而,在GTP存在的情况下荧光猝灭最大,其次是ATP,这表明GTP是优先配体。用不同浓度的GTP进行荧光猝灭程度来计算结合常数,发现其为3 μM,低于其他能结合NTP的蛋白质的报道值。这是关于任何番茄斑萎病毒属病毒的NSm的GTP和ATP结合特性的首次报道。此外,NSm还能水解GTP。初步序列分析表明,在氨基酸序列51 - 58和267 - 274处存在两个推定的非典型沃克A基序,表明该序列可能参与NTP结合。这个基序在大多数番茄斑萎病毒属病毒中是保守的。来自亚洲分支的GBNV的NSm定位于内质网网络并将其重塑为囊泡,有人提出这与通过胞间连丝(PD)的运动有关。因此,GTP - NSm相互作用可能参与细胞间运输的信号传导。