Yerlikaya Zeynep, Miranda-CasoLuengo Raúl, Yin Yuting, Cheng Cheng, Meijer Wim G
UCD School of Biomolecular and Biomedical Science and UCD Conway Institute, University College Dublin, Dublin, Ireland.
Department of Microbiology, School of Veterinary Medicine, Firat University, Elazığ, Türkiye.
PLoS One. 2025 Jan 6;20(1):e0316541. doi: 10.1371/journal.pone.0316541. eCollection 2025.
The multi-host pathogen Rhodococcus equi is a parasite of macrophages preventing maturation of the phagolysosome, thus creating a hospitable environment supporting intracellular growth. Virulent R. equi isolated from foals, pigs and cattle harbor a host-specific virulence plasmid, pVAPA, pVAPB and pVAPN respectively, which encode a family of 17 Vap proteins belonging to seven monophyletic clades. We examined all 17 Vap proteins for their ability to complement intracellular growth of a R. equi ΔvapA strain, and show that only vapK1, vapK2 and vapN support growth in murine macrophages of this strain. We show that only the clade-1 proteins VapA, VapK1, VapK2 and VapN are located on the R. equi cell surface. The pVAPB plasmid encodes three clade-1 proteins: VapK1, VapK2 and VapB. The latter was not able to support intracellular growth and was not located on the cell surface. We previously showed that the unordered N-terminal VapA sequence is involved in cell surface localisation of VapA. We here show that although the unordered N-terminus of the 17 Vap proteins is highly variable in length and sequence, it is conserved within clades, which is consistent with our observation that the N-terminus of clade-1 Vap proteins plays a role in cell surface localisation.
多宿主病原菌马红球菌是巨噬细胞的寄生虫，可阻止吞噬溶酶体成熟，从而营造出支持细胞内生长的适宜环境。从马驹、猪和牛中分离出的强毒力马红球菌分别携带宿主特异性毒力质粒pVAPA、pVAPB和pVAPN，这些质粒编码属于7个单系分支的17种Vap蛋白家族。我们检测了所有17种Vap蛋白补充马红球菌ΔvapA菌株细胞内生长的能力，结果表明只有vapK1、vapK2和vapN能支持该菌株在小鼠巨噬细胞中的生长。我们发现只有分支1蛋白VapA、VapK1、VapK2和VapN位于马红球菌细胞表面。pVAPB质粒编码三种分支1蛋白：VapK1、VapK2和VapB。后者不能支持细胞内生长，也不在细胞表面定位。我们之前表明无序的VapA N端序列参与VapA的细胞表面定位。我们在此表明，尽管17种Vap蛋白的无序N端在长度和序列上高度可变，但在各分支内是保守的，这与我们观察到的分支1 Vap蛋白的N端在细胞表面定位中起作用一致。
