Functional roles of conserved amino acid residues surrounding the phosphorylatable histidine of the yeast phosphorelay protein YPD1

• Published in: Molecular microbiology Vol. 37; no. 1; pp. 136 - 144
• Main Authors: Janiak‐Spens, Fabiola, West, Ann H.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.07.2000; Blackwell Publishing Ltd
• Subjects: Amino Acids - chemistry; Amino Acids - metabolism; Bacterial Proteins; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - metabolism; Histidine - chemistry; Histidine - metabolism; Intracellular Signaling Peptides and Proteins; Membrane Proteins - metabolism; Methyl-Accepting Chemotaxis Proteins; Models, Molecular; Mutagenesis, Site-Directed; Phosphorylation; Protein Kinases; Protein Structure, Tertiary; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins; YPD1 protein
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1046/j.1365-2958.2000.01973.x

The histidine‐containing phosphotransfer (HPt) protein YPD1 is an osmoregulatory protein in yeast that facilitates phosphoryl transfer between the two response regulator domains associated with SLN1 and SSK1. Based on the crystal structure of YPD1 and the sequence alignment of YPD1 with other HPt domains, we site‐specifically engineered and purified several YPD1 mutants in order to examine the role of conserved residues surrounding the phosphorylatable histidine (H64). Substitution of the positively charged residues K67 and R90 destabilized the phospho‐imidazole linkage, whereas substitution of G68 apparently reduces accessibility of H64. These findings, together with the effect of other mutations, provide biochemical support of the proposed functional roles of conserved amino acid residues of HPt domains.