SummaryTo obtain mutants for the study of the basic biology and pathogenic mechanisms of mycoplasmas, the insertion site of transposon Tn4001T was determined for 1700 members of a library of Mycoplasma pulmonis mutants. After evaluating several criteria for gene disruption, we concluded that 321 of the 782 protein coding regions were inactivated. The dispensable and essential genes of M. pulmonis were compared with those reported for Mycoplasma genitalium and Bacillus subtilis. Perhaps the most surprising result of the current study was that unlike other bacteria, ribosomal proteins S18 and L28 were dispensable. Carbohydrate transport and the susceptibility of selected mutants to UV irradiation were examined to assess whether active transposition of Tn4001T within the genome would confound phenotypic analysis. In contrast to earlier reports suggesting that mycoplasmas were limited in their DNA repair machinery, mutations in recA, uvrA, uvrB and uvrC resulted in a DNA-repair deficient phenotype. A mutant with a defect in transport of N-acetylglucosamine was identified.
The genomes of several species of mycoplasma have been sequenced. Most of these species rely on the glycolytic pathway for energy production, with the one exception of Ureaplasma, a species that breaks down urea as its principle source of acquiring energy. Several species, including as Mycoplasma arthritidis, are nonglycolytic and can use arginine as their source of energy. Described here are the genome sequence and a transposon library of M. arthritidis. The genome of 820,453 bp is typical in size for a mycoplasma and contains two large families of genes that are predicted to code for phase-variable proteins. The transposon library was constructed using a minitransposon that inserts stably into the mycoplasma genome. Of the 635 predicted coding regions, 218 were disrupted in a library of 1,100 members. Dispensable genes included the gene coding for the MAM superantigen and genes coding for ribosomal proteins S15, S18, and L15.Mycoplasma arthritidis is a natural pathogen of rats, causing severe polyarthritis. Arthritis in mice can be experimentally induced by injection of M. arthritidis into the tail vein. Disease in mice is more chronic than in rats, with lesions similar to those seen in human rheumatoid arthritis (25). Factors thought to contribute to the virulence of M. arthritidis are MAM, a potent superantigen secreted by the mycoplasma, and the M. arthritidis adhesins (MAAs) that have a role in cytadherence (32).The genome sequences of several species of mycoplasma are known (see http://cbi.labri.fr/outils/molligen/). Other than Ureaplasma, which utilizes the hydrolysis of urea to generate ATP, all of the mycoplasma species that have sequenced genomes are glycolytic. Some species of mycoplasma such as M. arthritidis are nonglycolytic, and thus it was anticipated that the sequence of the M. arthritidis genome would reveal new aspects of mycoplasma physiology. Nonglycolytic mycoplasmas generally catabolize arginine as a major source of energy, and, indeed, the required genes for arginine catabolism were identified in the genome sequence of M. arthritidis.Described here is the genome sequence of the virulent M. arthritidis strain 158L3-1 (3, 31). Strain 158L3-1 is a lysogen containing the 16-kb genome of the MAV1 bacteriophage. No additional prophages were noted in the genome. The sequence revealed features offering insight into the mechanisms by which the mycoplasma causes chronic inflammation, including two families of genes that are predicted to code for phasevariable proteins and a predicted gene product related to but distinct from MAM.We also describe a transposon library of M. arthritidis strain 158, the nonlysogenic parent of 158L3-1. The library was created using minitransposons derived from Tn4001 that inserts into the genome at essentially random sites. The genomic location of the minitransposon was determined for 1,113 library members. Using criteria for gene inactivation previously developed for transposon mutagenesis of Mycoplasma pulmonis, 218 of the predicted protein coding regions, including ...
Higher trans fat intake is associated with an increased risk of all-cause mortality.
We describe here mutants of Mycoplasma pulmonis that were obtained by using a minitransposon, Tn4001TF1, which actively transposes but is then unable to undergo subsequent excision events. Using Tn4001TF1, we disrupted 39 genes previously thought to be essential for growth. Thus, the number of genes required for growth has been overestimated. This study also revealed evidence of gene duplications in M. pulmonis and identified chromosome segregation proteins that are dispensable in mycoplasmas but essential in Bacillus subtilis.
Constitutional LZTR1 or SMARCB1 pathogenic variants (PVs) have been found in ∼86% of familial and ∼40% of sporadic schwannomatosis cases. Hence, we performed massively parallel sequencing of the entire LZTR1, SMARCB1, and NF2 genomic loci in 35 individuals with schwannomas negative for constitutional first‐hit PVs in the LZTR1/SMARCB1/NF2 coding sequences; however, with 22q deletion and/or a different NF2 PV in each tumor, including six cases with only one tumor available. Furthermore, we verified whether any other LZTR1/SMARCB1/NF2 (likely) PVs could be found in 16 cases carrying a SMARCB1 constitutional variant in the 3′‐untranslated region (3′‐UTR) c.*17C>T, c.*70C>T, or c.*82C>T. As no additional variants were found, functional studies were performed to clarify the effect of these 3′‐UTR variants on the transcript. The 3′‐UTR variants c.*17C>T and c.*82C>T showed pathogenicity by negatively affecting the SMARCB1 transcript level. Two novel deep intronic SMARCB1 variants, c.500+883T>G and c.500+887G>A, resulting in out‐of‐frame missplicing of intron 4, were identified in two unrelated individuals. Further resequencing of the entire repeat‐masked genomics sequences of chromosome 22q in individuals negative for PVs in the SMARCB1/LZTR1/NF2 coding‐ and noncoding regions revealed five potential schwannomatosis‐predisposing candidate genes, that is, MYO18B, NEFH, SGSM1, SGSM3, and SBF1, pending further verification.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.