InterPro domain: IPR001646

These repeats were first identified in many cyanobacterial proteins but they are also found in bacterial as well as in plant proteins [ 1 ]. The repeats were first identified in hglK [ 2 ]. Pentapeptide repeat proteins (PRPs) are characterised by the repetition of the pentapeptide repeat motif [S,T,A,V][D,N][L,F][S,T,R][G], which allows it to adopt a right-handed beta-helical structure conformation [ 3 ]. The functions of these repeats is unknown but it has been shown that members of this family share the ability to interact with DNA-binding proteins, such as DNA gyrase. For example, McbG (from Escherichia coli) protects the DNA gyrase from microcin B17 toxicity, MfpAMt (from Mycobacterium tuberculosis) and Qnr (from Klebsiella pneumoniae and other enterobacteria) are involved in resistance to fluoroquinolones [ 4 ].

1. Characterisation of an Arabidopsis cDNA encoding a thylakoid lumen protein related to a novel 'pentapeptide repeat' family of proteins. FEBS Lett. 428, 241-4
2. The hglK gene is required for localization of heterocyst-specific glycolipids in the cyanobacterium Anabaena sp. strain PCC 7120. J. Bacteriol. 177, 6440-8
3. Structure and distribution of pentapeptide repeats in bacteria. Protein Sci. 7, 1477-80
4. The pentapeptide repeat proteins MfpAMt and QnrB4 exhibit opposite effects on DNA gyrase catalytic reactions and on the ternary gyrase-DNA-quinolone complex. J. Bacteriol. 191, 1587-94