SUPERFAMILY 1.75 HMM library and genome assignments server

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Nitrogenase accessory factor-like superfamily

SCOP classification
Root:   SCOP hierarchy in SUPERFAMILY [ 0] (11)
Class:   Alpha and beta proteins (a/b) [ 51349] (147)
Fold:   Ribonuclease H-like motif [ 53066] (7)
Superfamily:   Nitrogenase accessory factor-like [ 53146] (2)
Families:   MTH1175-like [ 53147] (3)
  Nitrogenase accessory factor [ 102496]

Superfamily statistics
Genomes (640) Uniprot 2018_03 genome PDB chains (SCOP 1.75)
Domains 1,684 10,174 5
Proteins 1,679 10,131 5

Functional annotation
General category Other
Detailed category Unknown function

Function annotation of SCOP domain superfamilies

UniProtKB KeyWords (KW)

(show details)
KW termFDR (all)SDKW levelAnnotation (direct or inherited)
Biological processNitrogen fixation0Least InformativeDirect

Document: KW annotation of SCOP domains

InterPro annotation
Cross references IPR003731 SSF53146 Protein matches

This entry represents several Nif (B, X and Y) proteins, which are involved in the biosynthesis of the iron-molybdenum cofactor (FeMo-co) found in the dinitrogenase enzyme of the nitrogenase complex in nitrogen-fixing bacteria. The nitrogenase complex catalyses the reduction of atmospheric dinitrogen to ammonia, and is composed of an iron metalloprotein (dinitrogenase reductase; homodimer of NifH) and a Fe-Mo metalloprotein (dinitrogenase; heterotetramer of NifD and NifK). The pathway for the synthesis of the Fe-Mo cofactor involves several proteins, including NifB, NifE, NifH, NifN, NifQ, NifV and NifX. NifB appears to be an iron-sulphur source for FeMo-co biosynthesis, while NifX may be associated with the mature FeMo-co, in particular with the addition of homocitrate during the last step of biosynthesis [PubMed11279153]. The NifX protein shows sequence similarity with the C-terminus of NifB [PubMed12892890], as well as to the conserved protein MTH1175 from the archaeon Methanobacterium thermoautotrophicum, which displays a ribonuclease H-like motif of three layers, alpha/beta/alpha, with a single mixed beta-sheet [PubMed12836677].

InterPro database

PDBeMotif information about ligands, sequence and structure motifs
Cross references PDB entries
Ligand binding statistics
Nucleic-acid binding statistics
Occurrence of secondary structure elements
Occurrence of small 3D structural motifs

PDBeMotif resource

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Internal database links

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry out SCOP domain assignments to all genomes at the superfamily level.

Alignments of sequences to 6 models in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.

Browse and view proteins in genomes which have different domain combinations including a Nitrogenase accessory factor-like domain.

Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.

Explore domain occurrence network where nodes represent genomes and edges are domain architectures (shared between genomes) containing the superfamily of interest.

There are 6 hidden Markov models representing the Nitrogenase accessory factor-like superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.

Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation · UniProtKB KeyWords (KW) · Internal database links ]