Microcin

{{Short description|Class of very small bacterially produced peptide antibiotics}}

{{missing information|Microcin B17 and sagBCD family|date=December 2020}}

{{Infobox protein family

| Symbol = Subtilosin_A

| Name = Subtilosin_A

| image = PDB 1pxq EBI.jpg

| width =

| caption = structure of Subtilosin A

| Pfam = PF11420

| Pfam_clan =

| InterPro = IPR021539

| SMART =

| PROSITE =

| MEROPS =

| SCOP =

| TCDB = 1.C.84

| OPM family = 379

| OPM protein = 1pxq

| CAZy =

| CDD =

}}

Microcins are very small bacteriocins, composed of relatively few amino acids. For this reason, they are distinct from their larger protein cousins. The classic example is microcin V, of Escherichia 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.{{cite journal |vauthors=Kawulka KE, Sprules T, Diaper CM, Whittal RM, McKay RT, Mercier P, Zuber P, Vederas JC | title = 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 | journal = Biochemistry | volume = 43 | issue = 12 | pages = 3385–95 |date=March 2004 | pmid = 15035610 | doi = 10.1021/bi0359527 }}

Microcins produced by commensal E. coli strains target and eliminate enteric pathogens such as Salmonella enterica by mimicking the siderophores the pathogens use for iron scavenging.{{Cite journal|url=https://doi.org/10.1038/s41421-021-00253-6|doi=10.1038/s41421-021-00253-6|title=Structure of the mannose phosphotransferase system (Man-PTS) complexed with microcin E492, a pore-forming bacteriocin|year=2021|last1=Huang|first1=Kai|last2=Zeng|first2=Jianwei|last3=Liu|first3=Xueli|last4=Jiang|first4=Tianyu|last5=Wang|first5=Jiawei|journal=Cell Discovery|volume=7|issue=1|page=20|pmid=33820910|pmc=8021565}} Microcins also help commensal strains of E. coli outcompete pathogenic strains.{{cite journal| author=Sassone-Corsi M, Nuccio SP, Liu H, Hernandez D, Vu CT, Takahashi AA | display-authors=etal| title=Microcins mediate competition among Enterobacteriaceae in the inflamed gut. | journal=Nature | year= 2016 | volume= 540 | issue= 7632 | pages= 280–283 | pmid=27798599 | doi=10.1038/nature20557 | pmc=5145735 | bibcode=2016Natur.540..280S}}

BACTIBASE{{cite journal |title=BACTIBASE: a new web-accessible database for bacteriocin characterization |vauthors=Hammami R, Zouhir A, Ben Hamida J, Fliss I |journal=BMC Microbiology |year=2007 |volume=7 |pages=89 |pmid=17941971 |doi=10.1186/1471-2180-7-89 |pmc=2211298 |doi-access=free }}{{cite journal |title=BACTIBASE second release: a database and tool platform for bacteriocin characterization. |vauthors=Hammami R, Zouhir A, Le Lay C, Ben Hamida J, Fliss I |journal=BMC Microbiology |year=2010 |volume=10 |pages=22 |pmid=20105292 |doi=10.1186/1471-2180-10-22 |pmc=2824694 |doi-access=free }} database is an open-access database for bacteriocins including microcins.