Bacterial avidins are a widely distributed protein family in Actinobacteria, Proteobacteria and Bacteroidetes

Abstract

Background 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. Results 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. Conclusions 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.

Self‐assembly of a dimeric avidin into unique higher‐order oligomers

“…4A,B). Although agroavidin lacks the conserved Tyr, molecular evolutionary genetic analysis (MEGA6.0 ‐ not shown) indicates that agroavidin belongs to the same clade as the rest of the dimeric avidins between hoefavidin and affifavidin strengthening the notion that it will have a dimeric structure [25,26].…”

Wilavidin* — a novel member of the avidin family that forms unique biotin‐binding hexamers

“…Further experimental investigation is required to study the importance of this motif, yet the data indicate its possible involvement in maintaining the multimeric forms. Additional support to the relevance of this motif is its presence in predicted novel dimeric avidins [44], where wilavidin would indeed cluster with the dimers as it is similar to shwanavidin (sequence identity of 58.5%).…”

Effect of Cu addition on sedimentary bacterial community structure and heavy metal resistance gene abundance in mangrove wetlands

“…This might be explained by the different physiological and genetic characteristics of different bacterial communities. For example, a biotin-binding protein called bacterial avidin is found mainly in Proteobacteria and Bacteroidetes, which might be an important factor in the resistance of these taxonomic groups to environmental change (Laitinen et al, 2021). Compared with other dominant bacterial communities, the correlation in all samples between Nitrospira and environmental factors was extremely significant (P<0.01) (Table 4b).…”

“…Heavy metals, together with other environmental factors, influence the structure of sedimentary bacterial communities, which represent a vital component of the mangrove ecosystem (Hu et al, 2022). Changes in the sedimentary environment of mangroves can directly or indirectly affect the diversity, composition and metabolic activities of bacterial communities (Shannon et al, 2003;Lee et al, 2014;Echavarri-Bravo et al, 2015;Balakrishnan et al, 2017). When mangroves are polluted by excessive amounts of heavy metals, the microorganisms in sediments usually respond by expressing specific heavy-metal resistance genes (HMRGs).…”