Submitted to: Mycological Society of America
Publication Type: Abstract Only
Publication Acceptance Date: July 30, 2005
Publication Date: July 30, 2005
Citation: Mullaney, E.J., Ullah, A.H. 2005. Conservation of an eight-cysteine motif in fungal histidine acid phosphatases (abstract). Mycological Society of America. p. 169. Technical Abstract: A survey of known amino acid sequence of a number of fungal histidine acid phosphatases (HAP) has revealed a conserved eight-cysteine motif (8CM). Typically, conserved amino acid sequences have been associated with catalytic or structurally essential components for the functionality of a protein. The catalytic mechanism of HAPs is known, and no cysteines are involved in catalysis. Therefore, the HAP’s 8CM appears to have been conserved because they are involved in the formation of key disulfide bridges. X-ray crystallographic data of Aspergillus niger myo-inositol hexakisphosphate and a few other fungal HAPs have revealed that all eight cysteines are components of disulfide bridges. While 3-D molecular models for all fungal HAPs are not available, the unique pattern of conservation supports a similar critical role for these amino acids in all these HAPs sequences. A different 8CM has recently been reported from a survey of plant databases. Almost 500 different plant polypeptides having various functions all shared a unique cysteine motif, which like the HAP cysteines has no catalytic function. Rather, it appears that both the plant and the HAP 8CM have been conserved to provide the essential tertiary structure of the molecule for maintaining both a functional active site and a substrate-binding domain.