Journal:JBIC:14

Multifaceted SlyD from Helicobacter pylori: implication in [NiFe] hydrogenase maturation

Tianfan Cheng, Hongyan Li, Wei Xia and Hongzhe Sun^[1]

Molecular Tour
SlyD belongs to the FK506-binding protein (FKBP) family with both peptidylprolyl isomerase (PPIase) and chaperone activities, and is considered to be a ubiquitous cytosolic protein-folding facilitator in bacteria. It possesses a histidine- and cysteine-rich C-terminus binding to selected divalent metal ions (e.g., Ni²⁺, Zn²⁺), which is important for its involvement in the maturation processes of metalloenzymes. We have determined the solution structure of from Helicobacter pylori (HpSlyDΔC). HpSlyDΔC folds into the PPIase-active FKBP domain (in cyan) and the chaperone-active insert-in-flap (IF) domain (in red), linkers are in darkmagenta. The FKBP domain consists of a four-stranded antiparallel Intact H. pylori SlyD binds both Ni²⁺ and Zn²⁺, with dissociation constants of 2.74 and 3.79 μM respectively. Intriguingly, binding of Ni²⁺ instead of Zn²⁺ induces protein conformational changes around the (residues experiencing relatively large chemical shift perturbations upon interactions of HpSlyDΔC with Ni²⁺ are in blueviolet). (residues in orange). Surprisingly, several residues (Ile41, Gly42, Ile46, and Asn31) were from the FKBP domain, which is likely due to the binding of the longer n-region of HydA Tat peptide to the FKBP domain. Nickel binding and the recognition of the Tat signal peptide by the protein suggest that SlyD participates in [NiFe] hydrogenase maturation processes.