Details

Autor(en) / Beteiligte

• Saini, Gunjan
• Sharma, Nidhi
• Dalal, Vikram
• Warghane, Ashish
• Ghosh, Dilip Kumar
• Kumar, Pravindra
• Sharma, Ashwani Kumar

Titel

The analysis of subtle internal communications through mutation studies in periplasmic metal uptake protein CLas-ZnuA2

Ist Teil von

• Journal of structural biology, 2018-11, Vol.204 (2), p.228-239

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2018

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The superposition involving metal-free states of S38A CLas-ZnuA2 (green) and wild-type CLas-ZnuA2 (pink) (PDBID:4UDN) showing variation in secondary structure elements in C-domain is shown. [Display omitted] •Mutation studies to analyze role of critical residues in CLas-ZnuA2 structure.•Except for S38A and Y68F, all resulted in destabilization/degradation of protein.•Crystal structures of S38A and Y68F showed substantial changes in conformation.•Variation in interactions suggested changes in subtle internal communications.•Any change in critical residues can disturb the fine-tuned structure and mechanism. The subtle internal communications through an intricate network of interactions play a key role in metal-binding and release in periplasmic metal uptake proteins of cluster A-I family, a component of ABC transport system. These proteins have evolved different mechanisms of metal-binding and release through sequence and thereby structure-function divergence. The CLas-ZnuA2 from Candidatus Liberibacter asiaticus (CLA), in previous studies, showed a lower metal-binding affinity. The subtle communications within and between domains from crystal structure analysis revealed that protein seems to prefer a metal-free state. The unique features of CLas-ZnuA2 included a highly restrained loop L3 and presence of a proline in linker helix. In present work, S38A and Y68F mutants were studied as they play an important role during metal-binding in CLas-ZnuA2. The mutations in linker helix could not be studied as the expressed protein was not soluble and in most cases degraded with time. The crystal structure analysis of (S38A and Y68F) mutants in metal-free and metal-bound forms showed variations in interactions, an increase in number of alternate conformations and distortions in secondary structure elements, despite a similar overall structure, suggesting alterations in internal communications. The results suggested that any change in critical residues could alter the subtle internal communications and result in disturbing the fine-tuned structure required for optimal functioning.