Database accession: MF7000857
Name: CafB, disulfide-bonded form (Aspergillus fumigatus)
PDB ID: 7cxx
Experimental method: X-ray (2.00 Å)
Assembly: Homodimer
Source organism: Aspergillus fumigatus
Primary publication of the structure:
Kim S, Yeon J, Sung J, Kim NJ, Hong S, Jin MS
Structural insights into novel mechanisms of inhibition of the major β-carbonic anhydrase CafB from the pathogenic fungus Aspergillus fumigatus.
(2021) J. Struct. Biol. 213: 107700
PMID: 33545350
Abstract:
In fungi the β-class of carbonic anhydrases (β-CAs) are zinc metalloenzymes that are essential for growth, survival, differentiation, and virulence. Aspergillus fumigatus is the most important pathogen responsible for invasive aspergillosis and possesses two major β-CAs, CafA and CafB. Recently we reported the biochemical characterization and 1.8 Å crystal structure of CafA. Here, we report a crystallographic analysis of CafB revealing the mechanism of enzyme catalysis and establish the relationship of this enzyme to other β-CAs. While CafA has a typical open conformation, CafB, when exposed to acidic pH and/or an oxidative environment, has a novel type of active site in which a disulfide bond is formed between two zinc-ligating cysteines, expelling the zinc ion and stabilizing the inactive form of the enzyme. Based on the structural data, we generated an oxidation-resistant mutant (Y159A) of CafB. The crystal structure of the mutant under reducing conditions retains a catalytic zinc at the expected position, tetrahedrally coordinated by three residues (C57, H113 and C116) and an aspartic acid (D59), and replacing the zinc-bound water molecule in the closed form. Furthermore, the active site of CafB crystals grown under zinc-limiting conditions has a novel conformation in which the solvent-exposed catalytic cysteine (C116) is flipped out of the metal coordination sphere, facilitating release of the zinc ion. Taken together, our results suggest that A. fumigatus use sophisticated activity-inhibiting strategies to enhance its survival during infection.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
carbonate dehydratase activity carbonate dehydratase activity
zinc ion binding zinc ion binding
Biological process:
carbon utilization carbon utilization
cellular response to carbon dioxide cellular response to carbon dioxide
cellular response to oxidative stress cellular response to oxidative stress
Cellular component:
cytoplasm cytoplasm
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: All chains according to the most probable oligomerization state stored in PDBe were considered.
Number of unique protein segments: 1
Name: Carbonic anhydrase
Source organism: Aspergillus fumigatus
Length: 228 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMEPSDQKVDTVPQYLKQSHERIFENNRAWVATKMKDDPAFFEKLSAGQTPEYLYIGCSDSRVPANEIMGLEAGEVFVHRNIANLVPNTDLNVMSVINYAVRHLQVKHIVVCGHYHCGGVKAALTPSDLGLLNPWLRNVRDVYRLHEQELDGIQDATARYRRLVELNVIESCRNVIKTAAVQQSFHERQFPVVHGWIFDVETGLLRDLEIDFEETLRDIKKIYNLAPGS
UniProtKB AC: A4DA32 (positions: 9-224)
Coverage: 94%
Name: Carbonic anhydrase
Source organism: Aspergillus fumigatus
Length: 228 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMEPSDQKVDTVPQYLKQSHERIFENNRAWVATKMKDDPAFFEKLSAGQTPEYLYIGCSDSRVPANEIMGLEAGEVFVHRNIANLVPNTDLNVMSVINYAVRHLQVKHIVVCGHYHCGGVKAALTPSDLGLLNPWLRNVRDVYRLHEQELDGIQDATARYRRLVELNVIESCRNVIKTAAVQQSFHERQFPVVHGWIFDVETGLLRDLEIDFEETLRDIKKIYNLAPGS
UniProtKB AC: A4DA32 (positions: 21-221)
Coverage: 88%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: Carbonic anhydrase
Evidence level: Indirect evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
The native carbonic anhydrase is dimeric in solution, in agreement with being a tightly associated dimer with a large, hydrophobic buried surface area. The extended β-sheet core consisting of ten β–strands is equally contributed by the two monomers, and the N-terminal helix of each monomer extends around the other monomer. Based on the highly intertwined structure, the monomeric form is most probably not a stable, independently folding unit. The two active sites are also located in clefts at the dimeric interface, further suggesting that dimer is the functional form (PMID:32515610).
Chain A:
N/A
Chain B:
N/A
Surface and contacts features:
Structures from the PDB that contain the same number of proteins, and the proteins from the two structures show a sufficient degree of pairwise similarity, i.e. they belong to the same UniRef90 cluster (the full proteins exhibit at least 90% sequence identity) and convey roughly the same region to their respective interactions (the two regions from the two proteins share a minimum of 70% overlap). Download the CIF file (.cif)
Download this entry's XML file (.xml)
Download this entry's JSON file (.json)
