Dissecting the Cdc37 Co-chaperone Code: Functional Roles in Chaperone-Mediated Stress Adaptation.

Cdc37 is a kinase-specific co-chaperone that scaffolds protein kinase clients to the Hsp90 chaperone system. Although phosphorylation at residues S14 and S17 is known to regulate Cdc37 function, the broader role of phosphorylation across the protein remains unclear. To systematically investigate this, we created a "Cdc37 code collection," a set of 46 yeast strains expressing single phospho-site mutants of Cdc37, and performed phenotypic profiling across a wide panel of environmental and chemical stressors. While canonical sites like S14 and S17 were essential for stress tolerance, 34 additional phospho-mutants exhibited distinct phenotypes, often in a stress-specific manner. Notably, the mutations displayed little overlap in their stress responses, suggesting a modular and context-dependent regulation of Cdc37. Our data reveal that Cdc37 function is intricately modulated by site-specific phosphorylation, which shapes its capacity to maintain proteostasis under diverse cellular conditions. This study provides a comprehensive resource for dissecting the functional landscape of Cdc37 post-translational regulation and highlights new regulatory sites with potential relevance to chaperone-kinase network dysregulation in disease.