View in Gene3D

CATH Superfamily 3.40.50.1400

The name of this superfamily has been modified since the most recent official CATH+ release (v4_3_0). At the point of the last release, this superfamily was: waiting to be named.

Functional Families

Overview of the Structural Clusters (SC) and Functional Families within this CATH Superfamily. Clusters with a representative structure are represented by a filled circle.
« Back to all FunFams

FunFam 31: Sirohydrochlorin cobaltochelatase CbiKP

There are 2 EC terms in this cluster

Please note: EC annotations are assigned to the full protein sequence rather than individual protein domains. Since a given protein can contain multiple domains, it is possible that some of the annotations below come from additional domains that occur in the same protein, but have been classified elsewhere in CATH.

Note: The search results have been sorted with the annotations that are found most frequently at the top of the list. The results can be filtered by typing text into the search box at the top of the table.

EC Term Annotations Evidence
Sirohydrochlorin cobaltochelatase. [EC: 4.99.1.3]
Cobalt-sirohydrochlorin + 2 H(+) = sirohydrochlorin + Co(2+).
  • This enzyme is a type II chelatase, being either a monomer (CbiX) or a homodimer (CibK) and being ATP-independent.
  • CbiK from Salmonella enterica uses precorrin-2 as the substrate to yield cobalt-precorrin-2.
  • The enzyme contains two histidines at the active site that are thought to be involved in the deprotonation of the tetrapyrrole substrate as well as in metal binding.
  • CbiX from Bacillus megaterium inserts cobalt at the level of sirohydrochlorin (factor-II) rather than precorrin-2.
 4 A0A0E0SZS7 A0A0E0SZS7 Q72EC8 Q72EC8
Sirohydrochlorin ferrochelatase. [EC: 4.99.1.4]
Siroheme + 2 H(+) = sirohydrochlorin + Fe(2+).
  • This enzyme catalyzes the third of three steps leading to the formation of siroheme from uroporphyrinogen III.
  • The first step involves the donation of two S-adenosyl-L-methionine- derived methyl groups to carbons 2 and 7 of uroporphyrinogen III to form precorrin-2 (EC 2.1.1.107) and the second step involves an NAD(+)-dependent dehydrogenation to form sirohydrochlorin from precorrin-2 (EC 1.3.1.76).
  • In Saccharomyces cerevisiae, the last two steps are carried out by a single bifunctional enzyme, Met8p.
  • In some bacteria, steps 1-3 are catalyzed by a single multifunctional protein called CysG, whereas in Bacillus megaterium, three separate enzymes carry out each of the steps, with SirB being responsible for the above reaction.
 4 A0A0E0SZS7 A0A0E0SZS7 Q72EC8 Q72EC8