Chromosomal instability in Streptomyces avermitilis: major deletion in the central region and stable circularized chromosome.
Summary of "Chromosomal instability in Streptomyces avermitilis: major deletion in the central region and stable circularized chromosome."
The chromosome of Streptomyces has been shown to be unstable, frequently undergoing gross chromosomal rearrangements. However, the mechanisms underlying this phenomenon remain unclear, with previous studies focused on two chromosomal ends as targets for rearrangements. Here we investigated chromosomal instability of Streptomyces avermitilis, an important producer of avermectins, and characterized four gross chromosomal rearrangement events, including a major deletion in the central region. The present findings provide a valuable contribution to the mechanistic study of genetic instability in Streptomyces.
Thirty randomly-selected "bald" mutants derived from the wild-type strain all contained gross chromosomal rearrangements of various types. One of the bald mutants, SA1-8, had the same linear chromosomal structure as the high avermectin-producing mutant 76-9. Chromosomes of both strains displayed at least three independent chromosomal rearrangements, including chromosomal arm replacement to form new 88-kb terminal inverted repeats (TIRs), and two major deletions. One of the deletions eliminated the 36-kb central region of the chromosome, but surprisingly did not affect viability of the cells. The other deletion (74-kb) was internal to the right chromosomal arm. The chromosome of another bald mutant, SA1-6, was circularized with deletions at both ends. No obvious homology was found in all fusion sequences. Generational stability analysis showed that the chromosomal structure of SA1-8 and SA1-6 was stable.
Various chromosomal rearrangements, including chromosomal arm replacement, interstitial deletions and chromosomal circularization, occurred in S. avermitilis by non-homologous recombination. The finding of an inner deletion involving in the central region of S. avermitilis chromosome suggests that the entire Streptomyces chromosome may be the target for rearrangements, which are not limited, as previously reported, to the two chromosomal ends.
This article was published in the following journal.
Name: BMC microbiology
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20653985
- DOI: http://dx.doi.org/10.1186/1471-2180-10-198
Avermectins produced by Streptomyces avermitilis are commercially important anthelmintic agents. The detailed regulatory mechanisms of avermectin biosynthesis remain unclear. Here, we identified SAV36...
We describe the first postnatal diagnosis of a child from Central Brazil with de novo cytogenetic alterations in 13q showing malformations of the brain, eyes, distal limbs, and genitourinary tract, an...
Many chromosomal deletions encompassing the 2q23.1 region have been described ranging from small deletions of 38 kb up to >19 Mb. Most phenotypic features of the 2q23.1 deletion syndrome are due t...
Streptomyces avermitilis contains 33 cytochrome P450 genes in its genome, many of which play important roles in the biosynthesis process of antimicrobial agents. Here, we characterized the biochemical...
Aim: Study is devoted to evaluation of sensitivity of peripheral blood T-lymphocytes (PBL) of patients with endometrial cancer (EC) to genotoxic effect of bleomycin and detection of patients with hidd...
We are evaluating the incidence of significant hematological response, according to IWG criteria including CR, PR or, major HI, (HI-E, Hl-N,or Hl- P), and cytogenetic response of patients ...
The purposes of this study are to: 1. study the nature and longitudinal course of psychiatric symptoms in children with the 22q11.2 deletion syndrome and 2. identify genes...
Ankle sprain is the most occurring sport related injury. In addition, 40% of the people who sustain such an injury display residual symptoms under the general denominator functional ankle ...
Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the mammalian central nervous system. It is involved in a wide spectrum of physiological functions, from slee...
22q11.2 deletion syndrome is a genetic disorder that can cause heart defects, facial abnormalities, and developmental and learning disabilities. The severity of the disorder can vary widel...
Medical and Biotech [MESH] Definitions
Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)
A type of chromosomal aberration involving DNA BREAKS. Chromosome breakage can result in CHROMOSOMAL TRANSLOCATION; CHROMOSOME INVERSION; or SEQUENCE DELETION.
A mutation named with the blend of insertion and deletion. It refers to a length difference between two ALLELES where it is unknowable if the difference was originally caused by a SEQUENCE INSERTION or by a SEQUENCE DELETION. If the number of nucleotides in the insertion/deletion is not divisible by three, and it occurs in a protein coding region, it is also a FRAMESHIFT MUTATION.
An increased tendency to acquire CHROMOSOME ABERRATIONS when various processes involved in chromosome replication, repair, or segregation are dysfunctional.
A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.