Recent Characterization of Key Proteins to Combat Tuberculosis.

Recent large-scale proteogenomic analyses of Mycobacterium tuberculosis (Mtb) have significantly deepened our understanding of its proteome by delineating two major classes of proteins: canonical proteins and microproteins. Canonical proteins, encoded by well-annotated open reading frames (ORFs), perform essential functions in fundamental cellular processes, including DNA replication, metabolism, virulence regulation, and adaptation to stress. Concurrently, growing attention has been directed toward microproteins, small polypeptides translated from previously unannotated small ORFs, which have increasingly been recognized as key modulators of bacterial growth, persistence, and antibiotic response. Microproteins commonly exhibit structural characteristics such as intrinsically disordered regions, signal peptides, and transmembrane domains, enabling their participation in diverse cellular pathways, including membrane dynamics, signal transduction, and transcriptional regulation. These insights highlight the remarkable regulatory complexity and proteomic versatility that underpin Mtb's ability to adapt to host-imposed stress conditions. A significant advancement is the emerging understanding of conserved hypothetical proteins (CHPs), a long-overlooked group previously considered functionally ambiguous. Recent structural and functional characterizations have uncovered critical roles for many CHPs in vital biological processes, such as cell wall biosynthesis, DNA maintenance, metabolic control, and environmental stress responses. Notably, several newly characterized members of both microproteins and CHPs have surfaced as promising vaccine candidates owing to their strong immunogenicity and as attractive drug targets due to their essentiality and amenability to structural studies. Additionally, some exhibit potential as diagnostic biomarkers based on their infection-specific expression and recognition by the host immune system. Collectively, this expanded repertoire, especially the newly characterized proteins, significantly enhances our understanding of Mtb pathogenesis, adaptability, and persistence.