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PDB 1pxq EBI.jpg
structure of Subtilosin A
Symbol Subtilosin_A
Pfam PF11420
InterPro IPR021539
TCDB 1.C.84
OPM superfamily 508
OPM protein 1pxq

Microcins are very small bacteriocins, composed of a relatively few peptides. For this reason, they are distinct from their larger protein cousins. The classic example is microcin V, of E. coli. Subtilosin A is another bacteriocin from Bacillus subtilis. The peptide has a cyclized backbone and forms three cross-links between the sulphurs of Cys13, Cys7 and Cys4 and the alpha-positions of Phe22,Thr28 and Phe31.[1]

It is found that these bacteriocins target and eliminate iron-starved pathogens, which is found specifically in an inflamed gut where the E. Coli strain prefer to thrive. Specifically, the protein targets the pathogens are producing iron-scavenging protein in response to a low iron environment. Researchers found. E. coli Nissle’s microcins killed diarrhea-inducing bacteria called Salmonella Enterica in the guts of infected mice. Microcins also helped Nissle outcompete a different, more virulent of E. coli found in the infected mice's guts.[2]

BACTIBASE[3][4] database is an open-access database for bacteriocins including microcins.


  1. ^ Kawulka KE, Sprules T, Diaper CM, Whittal RM, McKay RT, Mercier P, Zuber P, Vederas JC (March 2004). "Structure of subtilosin A, a cyclic antimicrobial peptide from Bacillus subtilis with unusual sulfur to alpha-carbon cross-links: formation and reduction of alpha-thio-alpha-amino acid derivatives". Biochemistry. 43 (12): 3385–95. doi:10.1021/bi0359527. PMID 15035610. 
  2. ^ Tine Hesman Saey, [https://www.sciencenews.org/article/tiny-toxic-proteins-help-gut-bacteria-defeat-rivals?mode=topic&context=87 "Tiny toxic proteins help gut bacteria defeat rivals "], Science News Magazine Vol. 190, No. 12, December 10, 2016, p. 5
  3. ^ Hammami R, Zouhir A, Ben Hamida J, Fliss I (2007). "BACTIBASE: a new web-accessible database for bacteriocin characterization". BMC Microbiology. 7: 89. doi:10.1186/1471-2180-7-89. PMC 2211298Freely accessible. PMID 17941971. 
  4. ^ Hammami R, Zouhir A, Le Lay C, Ben Hamida J, Fliss I (2010). "BACTIBASE second release: a database and tool platform for bacteriocin characterization.". BMC Microbiology. 10: 22. doi:10.1186/1471-2180-10-22. PMC 2824694Freely accessible. PMID 20105292.