Putative zinc- or iron-chelating domain
This family of proteins contains 8 conserved cysteines. It has in the past been annotated as being one of the complex of proteins of the flagellar Fli complex. However this was due to a mis-annotation of the original Salmonella LT2 Genbank entry of 'fliB'. With all its conserved cysteines it is possibly a domain that chelates iron or zinc ions.
Jiyao W et al.(2023). "The conserved domain database in 2023.",