Biophysical characterization and ligand-binding properties of the elongation factor Tu from Mycobacterium tuberculosis

The Structural and Molecular Mechanisms of Mycobacterium tuberculosis Translational Elongation Factor Proteins

Targeting translation factor proteins holds promise for developing innovative anti-tuberculosis drugs. During protein translation, many factors cause ribosomes to stall at messenger RNA (mRNA). To maintain protein homeostasis, bacteria have evolved various ribosome rescue mechanisms, including the predominant trans-translation process, to release stalled ribosomes and remove aberrant mRNAs. The rescue systems require the participation of translation elongation factor proteins (EFs) and are essential for bacterial physiology and reproduction. However, they disappear during eukaryotic evolution, which makes the essential proteins and translation elongation factors promising antimicrobial drug targets. Here, we review the structural and molecular mechanisms of the translation elongation factors EF-Tu, EF-Ts, and EF-G, which play essential roles in the normal translation and ribosome rescue mechanisms of Mycobacterium tuberculosis (Mtb). We also briefly describe the structure-based, computer-assisted study of anti-tuberculosis drugs.

Structural and functional insights into macrophage migration inhibitory factor from Oncomelania hupensis, the intermediate host of Schistosoma japonicum

Oncomelania hupensis is the unique intermediate host of Schistosoma japonicum. As an irreplaceable prerequisite in the transmission and prevalence of schistosomiasis japonica, an in-depth study of this obligate host-parasite interaction can provide glimpse into the molecular events in the competition between schistosome infectivity and snail immune resistance. In previous studies, we identified a macrophage migration inhibitory factor (MIF) from O. hupensis (OhMIF), and showed that it was involved in the snail host immune response to the parasite S. japonicum. Here, we determined the crystal structure of OhMIF and revealed that there were distinct structural differences between the mammalian and O. hupensis MIFs. Noticeably, there was a projecting and structured C-terminus in OhMIF, which not only regulated the MIF's thermostability but was also critical in the activation of its tautomerase activity. Comparative studies between OhMIF and human MIF (hMIF) by analyzing the tautomerase activity, oxidoreductase activity, thermostability, interaction with the receptor CD74 and activation of the ERK signaling pathway demonstrated the functional differences between hMIF and OhMIF. Our data shed a species-specific light on structural, functional, and immunological characteristics of OhMIF and enrich the knowledge on the MIF family.