Chromoproteins: visible tools for advancing synthetic biology.

Chromoproteins (homologous to fluorescent proteins identified initially in marine organisms) are visible to the naked eye under white light. Their unique advantages - including robust expression in both prokaryotic and eukaryotic systems, broad color diversity, and tunability through genetic engineering - make them desirable tools for synthetic biology. This opinion article provides a comprehensive overview of recent progress in chromoprotein-based research, highlighting their physicochemical properties, detailed classification, engineering strategies, and emerging applications. We anticipate that ongoing discovery and rational design of chromoprotein variants will significantly advance the development of visible chromoprotein reporters, enabling more accessible and modular platforms for synthetic biology research and applications.