Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
Horticulture Technologies, Natural Resources Institute Finland, Turku, Finland.
BMC Ecol Evol. 2021 Apr 9;21(1):53. doi: 10.1186/s12862-021-01784-y.
Avidins are biotin-binding proteins commonly found in the vertebrate eggs. In addition to streptavidin from Streptomyces avidinii, a growing number of avidins have been characterized from divergent bacterial species. However, a systematic research concerning their taxonomy and ecological role has never been done. We performed a search for avidin encoding genes among bacteria using available databases and classified potential avidins according to taxonomy and the ecological niches utilized by host bacteria.
Numerous avidin-encoding genes were found in the phyla Actinobacteria and Proteobacteria. The diversity of protein sequences was high and several new variants of genes encoding biotin-binding avidins were found. The living strategies of bacteria hosting avidin encoding genes fall mainly into two categories. Human and animal pathogens were overrepresented among the found bacteria carrying avidin genes. The other widespread category were bacteria that either fix nitrogen or live in root nodules/rhizospheres of plants hosting nitrogen-fixing bacteria.
Bacterial avidins are a taxonomically and ecologically diverse group mainly found in Actinobacteria, Proteobacteria and Bacteroidetes, associated often with plant invasiveness. Avidin encoding genes in plasmids hint that avidins may be horizontally transferred. The current survey may be used as a basis in attempts to understand the ecological significance of biotin-binding capacity.
亲和素是普遍存在于脊椎动物卵中的生物素结合蛋白。除了来自链霉菌的链霉亲和素外，越来越多的亲和素已从不同的细菌物种中被鉴定出来。然而，针对它们的分类学和生态作用，还从未进行过系统的研究。我们利用现有的数据库在细菌中搜索亲和素编码基因，并根据分类学和宿主细菌利用的生态位对潜在的亲和素进行分类。
在放线菌门和变形菌门中发现了大量的亲和素编码基因。蛋白质序列的多样性很高，并且发现了几个新的编码生物素结合亲和素的基因变体。携带亲和素编码基因的细菌的生存策略主要分为两类。携带亲和素基因的细菌中，人类和动物病原体的数量过多。另一个广泛的类别是那些固氮或生活在固氮细菌的根瘤/根际中的细菌。
细菌亲和素是一个在分类学和生态学上都具有多样性的群体，主要存在于放线菌门、变形菌门和拟杆菌门中，常与植物的入侵性有关。质粒中的亲和素编码基因暗示亲和素可能发生水平转移。本研究可以作为尝试理解生物素结合能力的生态意义的基础。
