https://en.wikipedia.org/wiki/MCR-1
The "mobilized colistin resistance" ( mcr-1) gene confers plasmid-mediated resistance to colistin, a polymyxin and one of a number of last-resort antibiotics for treating infections. [1] [2] The gene is found in no less than ten species of the Enterobacteriaceae: Escherichia coli, Salmonella, Klebsiella pneumoniae, Enterobacter aerogenes

https://pubmed.ncbi.nlm.nih.gov/30036574/
The protein encoded by mcr1 is a putative 60-kDa phosphoethanolamine (pEtN) transferase, MCR-1, and has been studied extensively since its discovery. Herein, we present a comprehensive review of MCR-1 covering its structure, function, and mechanism, to call for the rational drug design of molecular inhibitors of MCR-1 to use in colistin-based

https://www.nature.com/articles/s41467-017-02149-0
MCR-1 is a lipid A modifying enzyme that confers resistance to the antibiotic colistin. Here, we analyse the impact of MCR-1 expression on E. coli morphology, fitness, competitiveness, immune

https://www.nature.com/articles/s41467-018-03205-z
For example, mcr-2 has 76.7% nucleotide identity to mcr-1 and was found in colistin-resistant isolates that did not contain mcr-1, and appeared to be mobilized on an IS1595 transposon 35.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8060599/
The mcr-1 gene was detected in 71.43%, almost all from milking cows, while both mcr-1 and mcr-2 genes were detectable in 3 cows. Zheng et al. (2019) examined faecal samples of 651 dairy cows in China in 2016, of which 290 contained ESBL-producing strains, and 3 were positive for the mcr-1 gene.

https://pubmed.ncbi.nlm.nih.gov/26603172/
The plasmid carrying mcr-1 was mobilised to an E coli recipient at a frequency of 10(-1) to 10(-3) cells per recipient cell by conjugation, and maintained in K pneumoniae and Pseudomonas aeruginosa. In an in-vivo model, production of MCR-1 negated the efficacy of colistin. MCR-1 is a member of the phosphoethanolamine transferase enzyme family

https://www.nature.com/articles/s41396-023-01509-7
In the case of mcr-1, this cost reflects the deleterious consequences of modifications to the bacterial cell surface mediated by MCR-1, and not the cost of MCR-1 protein synthesis per se (Fig. 2A).

https://www.nature.com/articles/s41467-018-02875-z
To determine if mcr-1 expression alters the rate at which colistin-mediated lysis occurs, we monitored the reduction of optical density (OD) over 18 h in wild-type and mcr-1-expressing E. coli.

https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005957
Author Summary Colistin is an ultimate line of refuge against fatal infections by multidrug-resistant Gram-negative pathogens. The plasmid-mediated transfer of the mobile colistin resistance gene (mcr-1) represents a novel mechanism for antibacterial drug resistance, and also poses new threats to public health. However, the mechanistic aspects of the MCR-1 colistin resistance are not fully

https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(20)30005-7/fulltext
The global dissemination of colistin resistance encoded by mcr-1 has been attributed to extensive use of colistin in livestock, threatening colistin efficacy in medicine. The emergence of mcr-1 in common pathogens, such as Escherichia coli, is of particular concern.China banned the use of colistin in animal feed from May 1, 2017. We investigated subsequent changes in mcr-1 prevalence in

https://www.cdc.gov/narms/resources/mcrgene.html
The mcr-1 gene is also important because of the role colistin plays in human medicine. Colistin is commonly used in other parts of the world in human and animal medicine. In the United States, colistin is not used to treat animals but is used as a last-resort drug to treat patients with multi-drug resistant infections caused by CRE, "the

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10896549/
Mobile colistin resistance (mcr) genes were described recently in Gram-negative bacteria including carbapenem-resistant Enterobacterales.There are ten mcr genes described in different Gram-negative bacteria, however, Escherichia coli harboring mcr-1 gene is by far the most frequent combination. In Argentina, mcr-1 gene was characterized only on plasmids belonging to IncI2 group.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6966882/
Colistin is considered the last-resort antibiotic used to treat multidrug resistant bacteria-related infections. However, the discovery of the plasmid-mediated colistin resistance gene, mcr-1, threatens the clinical utility of colistin antibiotics.In this study, the physiological function of MCR-1, which encodes an LPS-modifying enzyme, was investigated in E. coli K-12.

https://pubmed.ncbi.nlm.nih.gov/32514524/
The identification of the first mobile colistin resistance (MCR) gene, mcr-1, in 2015 triggered a rash of mcr screening reports. Subsequently, nine MCR-family genes and their variants have been described. However, a comprehensive overview concerning the epidemiology of the whole MCR family, which is essential for facilitating rational

https://www.sciencedirect.com/science/article/pii/S1359644618300254
MCR-1 is a type member of the pEtN transferase family along with its structural homologues, NmEptA and CjEptC, with which it shares ∼40% sequence identity [36]. The phylogenetic relationships of these homologues and other pEtN transferases are well described by Stogios et al.

https://www.cdc.gov/mmwr/volumes/65/wr/mm6536e2.htm
In 2015, scientists reported the emergence of the plasmid-encoded mcr-1 gene conferring bacterial resistance to the antibiotic colistin (1), signaling potential emergence of a pandrug-resistant bacterium.In May 2016, mcr-1-positive Escherichia coli was first isolated from a specimen from a U.S. patient (2) when a Pennsylvania woman was evaluated for a urinary tract infection.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5125707/
S4 Fig: Visualization for the transmembrane protein MCR-1.A. SDS-PAGE profile for the purified transmembrane protein MCR-1. B. Western blot analyses for the purified MCR-1 protein with the anti-6XHis tag primary antibody Designations: M, marker; kDa, kilo-dalton; WB, western blot. C. MS verification of the recombinant MCR-1 protein The tryptic peptides with 79.5% coverage to the MCR-1 sequence

https://pubmed.ncbi.nlm.nih.gov/33839987/
Therefore, the discovery of plasmid-mediated mobile colistin resistance (mcr) genes raised global public health concerns as they can spread by horizontal transfer and have chances of global dissemination. To date, ten slightly different variants of the mcr-1 gene (mcr-1 to mcr-10) have been identified in different bacteria isolated from animals

https://www.cidrap.umn.edu/antimicrobial-stewardship/highly-resistant-mcr-1-superbug-found-us-first-time
The MCR-1 sample is also resistant to ampicillin, streptomycin, sulfisoxazole, tetracycline, and other antibiotics. The USDA used a modified technique for detecting MCR-1, "employing a targeted and extremely sensitive method to examine whole bacterial populations found in intestinal samples from food-producing animals," according to the post

https://asm.org/ASM/media/CPHM/MCR-1-Guidelines-FINAL.pdf?ext=.pdf
The mcr-1 mcrgene was the first plasmid-mediated colistin resistance gene reported and, since then, ten dif-ferent variants of the mcr gene (named mcr-1 through mcr-10) have been identified around the world (4, 9). Because the mcr-1 gene continues to be the most predominant mcr type and the most frequently associated

https://www.cdc.gov/mmwr/volumes/65/wr/mm6536e3.htm
The mcr-1 gene confers resistance to the polymyxins, including the antibiotic colistin, a medication of last resort for multidrug-resistant infections. The mcr-1 gene was first reported in 2015 in food, animal, and patient isolates from China ( 1) and is notable for being the first plasmid-mediated colistin resistance mechanism to be identified.

https://nccid.ca/debrief/mobilized-colistin-resistance-mcr-1/
The mcr-1 gene has been found in the Enterobacteriaceae, a group of Gram negative bacteria. Most reports to date have identified the mcr-1 gene in E. coli, but it has also been reported from Salmonella species, Shigella sonnei, and K. pneumoniae as well as in E. aerogenes, and E . cloacae. The gene has been found in bacteria from food animals

https://www.lancastergeneralhealth.org/health-hub-home/2016/june/what-you-need-to-know-about-mcr1-and-antibioticresistant-superbugs
What is MCR-1? MCR-1 is not bacteria or a virus, but rather a gene—a piece of genetic material that allows a bacteria to become resistant to the antibiotic Colistin. Colistin is an old drug which today is used as a last resort to treat infections with bacteria that are already highly resistant to most other antibiotics. The MCR-1 gene has