Rapa Rita A, Labbate Maurizio
ithree Institute, University of Technology Sydney, NSW, Australia ; Department of Medical and Molecular Biosciences, University of Technology Sydney, NSW, Australia.
Front Microbiol. 2013 Dec 9;4:385. doi: 10.3389/fmicb.2013.00385.
The integron is a genetic element that incorporates mobile genes termed gene cassettes into a reserved genetic site via site-specific recombination. It is best known for its role in antibiotic resistance with one type of integron, the class 1 integron, a major player in the dissemination of antibiotic resistance genes across Gram negative pathogens and commensals. However, integrons are ancient structures with over 100 classes (including class 1) present in bacteria from the broader environment. While, the class 1 integron is only one example of an integron being mobilized into the clinical environment, it is by far the most successful. Unlike clinical class 1 integrons which are largely found on plasmids, other integron classes are found on the chromosomes of bacteria and carry diverse gene cassettes indicating a non-antibiotic resistance role(s). However, there is very limited knowledge on what these alternative roles are. This is particularly relevant to Vibrio species where gene cassettes make up approximately 1-3% of their entire genome. In this review, we discuss how emphasis on class 1 integron research has resulted in a limited understanding by the wider research community on the role of integrons in the broader environment. This has the capacity to be counterproductive in solving or improving the antibiotic resistance problem into the future. Furthermore, there is still a significant lack of knowledge on how gene cassettes in Vibrio species drive adaptation and evolution. From research in Vibrio rotiferianus DAT722, new insight into how gene cassettes affect cellular physiology offers new alternative roles for the gene cassette resource. At least a subset of gene cassettes are involved in host surface polysaccharide modification suggesting that gene cassettes may be important in processes such as bacteriophage resistance, adhesion/biofilm formation, protection from grazers and bacterial aggregation.
整合子是一种遗传元件，它通过位点特异性重组将称为基因盒的移动基因整合到一个保留的遗传位点。它因其在抗生素抗性中的作用而最为人所知，其中一种整合子，即1类整合子，是抗生素抗性基因在革兰氏阴性病原体和共生菌中传播的主要参与者。然而，整合子是古老的结构，在更广泛环境中的细菌中存在超过100个类别（包括1类）。虽然，1类整合子只是被转移到临床环境中的整合子的一个例子，但它是迄今为止最成功的。与主要存在于质粒上的临床1类整合子不同，其他整合子类别存在于细菌染色体上，并携带各种基因盒，表明其具有非抗生素抗性作用。然而，关于这些替代作用是什么的知识非常有限。这与弧菌属物种特别相关，其中基因盒约占其整个基因组的1-3%。在这篇综述中，我们讨论了对1类整合子研究的重视如何导致更广泛的研究群体对整合子在更广泛环境中的作用理解有限。这有可能在未来解决或改善抗生素抗性问题时适得其反。此外，关于弧菌属物种中的基因盒如何驱动适应和进化仍然存在重大知识空白。从对轮虫弧菌DAT722的研究中，对基因盒如何影响细胞生理学的新见解为基因盒资源提供了新的替代作用。至少一部分基因盒参与宿主表面多糖修饰，这表明基因盒可能在诸如噬菌体抗性、粘附/生物膜形成、免受捕食者侵害和细菌聚集等过程中很重要。
