Kyung-Kyu Kim

Pseudomonas aeruginosa is an opportunistic pathogen that synthesizes and secretes a wide range of virulence factors. P. aeruginosa poses a potential threat to human health worldwide due to its omnipresent nature, robust host accumulation, high virulence, and significant resistance to multiple antibiotics. The pathogenicity of P. aeruginosa, which is associated with acute and chronic infections, is linked with multiple virulence factors and associated secretion systems, such as the ability to for

ClpX, a heat shock protein 100 chaperone, which acts as the regulatory subunit of the ATP-dependent ClpXP protease, is responsible for intracellular protein remodeling and degradation. To provide a structural basis for a better understanding of the function of the Clp ATPase family, the crystal structures of Helicobacter pylori ClpX, lacking an N-terminal Cys cluster region complexed with ADP, was determined. The overall structure of ClpX is similar to that of heat shock locus U (HslU), consisti

Eukaryotic translation initiation factor 5A (eIF-5A) is a ubiquitous protein found in all eukaryotic cells. The protein is closely associated with cell proliferation in the G1-S stage of the cell cycle. Recent findings show that the eIF-5A proteins are highly expressed in tumor cells and act as a cofactor of the Rev protein in HIV-1-infected cells. The mature eIF is the only protein known to have the unusual amino acid hypusine, a post-translationally modified lysine. The crystal structure of eI

β-catenin is a key signal transducer in the canonical WNT pathway and is negatively regulated by ubiquitin-dependent proteolysis. Through screening of various deubiquitinating enzymes (DUBs), we identified ubiquitin specific protease 4 (USP4) as a candidate for β-catenin-specific DUB. The effects of USP4 overexpression or knockdown suggested that USP4 positively controls the stability of β-catenin and enhances β-catenin-regulated transcription. Domain mapping results revealed that the C-terminal

In response to fungal invasion and other signals, plants accumulate a number of proteins that are involved in defense against pathogens.1 Among these proteins, pathogenesis-related (PR) proteins are grouped into families based on primary structure, serological relatedness, and enzymatic and biological activities.2 Osmotin is a 24 kDa protein belonging to the PR-5 protein family whose members are homologous to the sweet-tasting protein thaumatin. Osmotin and other PR-5 proteins were shown to have

Z-DNA, a left-handed isoform of Watson and Crick’s B-DNA, is rarely formed without the help of high salt concentrations or negative supercoiling. However, Z-DNA-binding proteins can efficiently convert specific sequences of the B conformation into the Z conformation in relaxed DNA under physiological salt conditions. As in the case of many other specific interactions coupled with structural rearrangements in biology, it has been an intriguing question whether the proteins actively induce Z-DNAs

High temperature requirement A (HtrA) and its homologues constitute the HtrA familiy proteins, a group of heat shock-induced serine proteases. Bacterial HtrA proteins perform crucial functions with regard to protein quality control in the periplasmic space, functioning as both molecular chaperones and proteases. In contrast to other bacterial quality control proteins, including ClpXP, ClpAP, and HslUV, HtrA proteins contain no regulatory components or ATP binding domains. Thus, they are common

The receptor activator of nuclear factor-κB (RANK) and its ligand RANKL, which belong to the tumor necrosis factor (TNF) receptor-ligand family, mediate osteoclastogenesis. The crystal structure of the RANKL ectodomain (eRANKL) in complex with the RANK ectodomain (eRANK) combined with biochemical assays of RANK mutants indicated that three RANK loops (Loop1, Loop2, and Loop3) bind to the interface of a trimeric eRANKL. Loop3 is particularly notable in that it is structurally distinctive from oth