Title Structural basis for the ATP-independent proteolytic activity of LonB proteases and reclassification of their AAA+ modules
Author Young Jun An1, Jung-Hyun Na1, Myung-Il Kim1, and Sun-Shin Cha1,2,3*
Address 1Marine Biotechnology Research Center, Korea Institute of Ocean Science and Technology, Ansan 15627, Republic of Korea, 2Department of Marine Biotechnology, Korea University of Science and Technology, Daejeon 34113, Republic of Korea, 3Department of Convergence Study on the Ocean Science and Technology, Ocean Science and Technology School, Korea Maritime and Ocean University, Pusan 49112, Republic of Korea
Bibliography Journal of Microbiology, 53(10),711-717, 2015,
DOI 10.1007/s12275-015-5417-5
Key Words AAA+ proteins, PS-1 insert, H2 insert, Ins1, Lon proteases, Thermococcus onnurineus NA1, ATP-independent proteolytic activity
Abstract Lon proteases degrade defective or denature proteins as well as some folded proteins for the control of cellular protein quality. There are two types of Lon proteases, LonA and LonB. Each consists of two functional components: a protease component and an ATPase associated with various cellular activities (AAA+ module). Here, we report the 2.03 Å-resolution crystal structure of the isolated AAA+ module (iAAA+ module) of LonB from Thermococcus onnurineus NA1 (TonLonB). The iAAA+ module, having no bound nucleotide, adopts a conformation virtually identical to the ADP-bound conformation of AAA+ modules in the hexameric structure of TonLonB; this provides insights into the ATP-independent proteolytic activity observed in a LonB protease. Structural comparison of AAA+ modules between LonA and LonB revealed that the AAA+ modules of Lon proteases are separated into two distinct clades depending on their structural features. The AAA+ module of LonB belongs to the ‘H2 & Ins1 insert clade (HINS clade)’ defined for the first time in this study, while the AAA+ module of LonA is a member of the HCLR clade.