Identification of Key Amino Acid Residues Involved in the Localization of Sorting Nexin 10 and Induction of Vacuole Formation

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Bo Xiao^1,a, Nana Liu^2,b, Lixia Hou^1,c, Ming Jiang^3,d, and Dong Yao^1,3,4,e*

¹The Laboratory of Respiratory Disease, The Affiliated Hospital of Guilin Medical University, 541000 Guilin, China

²Department of Basic Medical Sciences, School of Nursing, Sanmenxia Polytechnic, 472000 Sanmenxia, China

³Department of Respiratory and Critical Care Medicine, The Affiliated Hospital of Guilin Medical University, 541000 Guilin, China

⁴The Key Laboratory of Respiratory Disease, Education Department of Guangxi Zhuang Autonomous Region, 541000 Guilin, China

^* To whom correspondence should be addressed.

Received April 8, 2021; Revised September 15, 2021; Accepted October 12, 2021

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Sorting nexin 10 (SNX10) induces formation of vacuoles participating in the endosome morphogenesis in mammalian cells, but the key amino acids involved in this function have not been fully identified. In this study, point mutations were introduced to the conserved region of the SNX10 PX domain to elucidate the function of these key amino acid residues. The number of vacuoles in the R53A mutant was partially decreased, while the R52A and R51A mutants completely lacked the vacuoles. All mutant proteins lost the phosphatidylinositol 3-phosphate (PtdIns3P)-binding ability and endosomal localization. Retargeting the mutants to the endosomes rescued partially or fully the vacuole-inducing ability in the R51A and R53A mutants, respectively, but not in the R52A mutant. No vacuoles were induced when the R51A mutant was targeted to other organelles. Structural analysis showed that Arg53 is responsible for the PtdIns(3)P binding, whereas Arg51 and Arg52 contribute to the structural integrity of SNX10. We conclude that the disruption of the key residues affects the structure and function of SNX10 and that induction of vacuole formation by SNX10 depends on its endosomal location.

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KEY WORDS: sorting nexin 10, PX domain, PtdIns(3)P binding, localization, vacuolation

DOI: 10.1134/S000629792111002X

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