MF7000857 CafB, disulfide-bonded form (Aspergillus fumigatus) 7cxx X-ray 2.00 Homodimer Aspergillus fumigatus 33545350 Kim S, Yeon J, Sung J, Kim NJ, Hong S, Jin MS J. Struct. Biol. 2021 1 213 107700 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. GO:0004089 carbonate dehydratase activity GO:0008270 zinc ion binding GO:0005737 cytoplasm GO:0015976 carbon utilization GO:0071244 cellular response to carbon dioxide GO:0034599 cellular response to oxidative stress 2 1 Homooligomeric enzymes Homodimeric enzymes All chains according to the most probable oligomerization state stored in PDBe were considered. A Carbonic anhydrase Aspergillus fumigatus A4DA32 9 224 94% MEPSDQKVDTVPQYLKQSHERIFENNRAWVATKMKDDPAFFEKLSAGQTPEYLYIGCSDSRVPANEIMGLEAGEVFVHRNIANLVPNTDLNVMSVINYAVRHLQVKHIVVCGHYHCGGVKAALTPSDLGLLNPWLRNVRDVYRLHEQELDGIQDATARYRRLVELNVIESCRNVIKTAAVQQSFHERQFPVVHGWIFDVETGLLRDLEIDFEETLRDIKKIYNLAPGS 228 secondary structure helix 12 37 secondary structure helix 39 46 secondary structure helix 63 68 secondary structure helix 81 84 secondary structure helix 89 102 secondary structure helix 116 122 secondary structure helix 130 151 secondary structure helix 154 176 secondary structure helix 177 188 secondary structure helix 210 223 secondary structure strand 52 57 secondary structure strand 75 80 secondary structure strand 107 112 secondary structure strand 191 197 secondary structure strand 204 206 pfam PF00484 Carbonic anhydrase 52 203 B Carbonic anhydrase Aspergillus fumigatus A4DA32 21 221 88% MEPSDQKVDTVPQYLKQSHERIFENNRAWVATKMKDDPAFFEKLSAGQTPEYLYIGCSDSRVPANEIMGLEAGEVFVHRNIANLVPNTDLNVMSVINYAVRHLQVKHIVVCGHYHCGGVKAALTPSDLGLLNPWLRNVRDVYRLHEQELDGIQDATARYRRLVELNVIESCRNVIKTAAVQQSFHERQFPVVHGWIFDVETGLLRDLEIDFEETLRDIKKIYNLAPGS 228 secondary structure helix 21 35 secondary structure helix 40 47 secondary structure helix 63 68 secondary structure helix 81 84 secondary structure helix 89 102 secondary structure helix 116 122 secondary structure helix 130 151 secondary structure helix 154 176 secondary structure helix 177 188 secondary structure helix 210 221 secondary structure strand 52 57 secondary structure strand 75 80 secondary structure strand 107 112 secondary structure strand 191 197 secondary structure strand 204 206 pfam PF00484 Carbonic anhydrase 52 203 Indirect evidence The full structure participates in mutual synergistic folding. Carbonic anhydrase 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). A N/A B N/A MF7000278 MF7000279 MF7000856 MF7000857 MF7000858 MF7000859