The Rab7 effector PLEKHM1 binds Arl8b to promote cargo traffic to lysosomes.
Endocytic, autophagic, and phagocytic vesicles move on microtubule tracks to fuse with lysosomes. Small GTPases, such as Rab7 and Arl8b, recruit their downstream effectors to mediate this transport and fusion. However, the potential cross talk between these two GTPases is unclear. Here, we show that the Rab7 effector PLEKHM1 simultaneously binds Rab7 and Arl8b, bringing about clustering and fusion of late endosomes and lysosomes. We show that the N-terminal RUN domain of PLEKHM1 is necessary and sufficient for interaction with Arl8b and its subsequent localization to lysosomes. Notably, we also demonstrate that Arl8b mediates recruitment of HOPS complex to PLEKHM1-positive vesicle contact sites. Consequently, Arl8b binding to PLEKHM1 is required for its function in delivery and, therefore, degradation of endocytic and autophagic cargo in lysosomes. Finally, we also show that PLEKHM1 competes with SKIP for Arl8b binding, which dictates lysosome positioning. These findings suggest that Arl8b, along with its effectors, orchestrates lysosomal transport and fusion.
Department of Biological Sciences, Indian Institute of Science Education and Research, Mohali, Punjab 140306, India.
Rituraj
R
Marwaha
Division of Cell Biology and Immunology, Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh 160036, India.
Subhash B
SB
Arya
Division of Cell Biology and Immunology, Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh 160036, India.
Divya
D
Jagga
Division of Cell Biology and Immunology, Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh 160036, India.
Harmeet
H
Kaur
Division of Cell Biology and Immunology, Council of Scientific and Industrial Research, Institute of Microbial Technology, Chandigarh 160036, India atuli@imtech.res.in msharma@iisermohali.ac.in.
Amit
0000-0001-5476-4127
A
Tuli
Department of Biological Sciences, Indian Institute of Science Education and Research, Mohali, Punjab 140306, India atuli@imtech.res.in msharma@iisermohali.ac.in.
Mahak
0000-0002-4117-4790
M
Sharma
D020727:ADP-Ribosylation Factors / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001343:Autophagy / Q000502:physiology; D001692:Biological Transport / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D011992:Endosomes / Q000378:metabolism / Q000502:physiology; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism* / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000090802:rab7 GTP-Binding Proteins
D048868:Adaptor Proteins, Signal Transducing; D008562:Membrane Glycoproteins; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; D020727:ADP-Ribosylation Factors; D020691:rab GTP-Binding Proteins