title: Structural basis for the ATP-independent proteolytic activity of LonB proteases and reclassification of their AAA+ modules.
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 -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.
authors.affiliation: Marine Biotechnology Research Center, Korea Institute of Ocean Science and Technology, Ansan, 15627, Republic of Korea.
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: An
authors.affiliation: Marine Biotechnology Research Center, Korea Institute of Ocean Science and Technology, Ansan, 15627, Republic of Korea.
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Na
authors.affiliation: Marine Biotechnology Research Center, Korea Institute of Ocean Science and Technology, Ansan, 15627, Republic of Korea.
authors.forename: Myung-Il
authors.initials: MI
authors.lastname: Kim
authors.affiliation: Marine Biotechnology Research Center, Korea Institute of Ocean Science and Technology, Ansan, 15627, Republic of Korea. chajung@kiost.ac.kr.|Department of Marine Biotechnology, Korea University of Science and Technology, Daejeon, 34113, Republic of Korea. chajung@kiost.ac.kr.|Department of Convergence Study on the Ocean Science and Technology, Ocean Science and Technology School, Korea Maritime and Ocean University, Pusan, 49112, Republic of Korea. chajung@kiost.ac.kr.
authors.forename: Sun-Shin
authors.initials: SS
authors.lastname: Cha
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D049070:Protease La / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017510:Protein Folding; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D019712:Thermococcus / Q000737:chemistry / Q000201:enzymology
chemical_list: D001426:Bacterial Proteins; D049070:Protease La; D000251:Adenosine Triphosphatases
keywords: AAA+ proteins; ATP-independent proteolytic activity; H2 insert; Ins1; Lon proteases; PS-1 insert; Thermococcus onnurineus NA1