Comparative Analyses of Transport Proteins Encoded within the Genomes of Bdellovibrio bacteriovorus HD100 and Bdellovibrio exovorus JSS

Abstract

Bdellovibrio, δ-proteobacteria, including B. bacteriovorus (Bba) and B. exovorus (Bex), are obligate predators of other Gram-negative bacteria. While Bba grows in the periplasm of the prey cell, Bex grows externally. We have analyzed and compared the transport proteins of these 2 organisms based on the current contents of the Transporter Classification Database (TCDB; www.tcdb.org). Bba has 103 transporters more than Bex, 50% more secondary carriers, and 3 times as many MFS carriers. Bba has far more metabolite transporters than Bex as expected from its larger genome, but there are 2 times more carbohydrate uptake and drug efflux systems, and 3 times more lipid transporters. Bba also has polyamine and carboxylate transporters lacking in Bex. Bba has more than twice as many members of the Mot-Exb family of energizers, but both may have energizers for gliding motility. They use entirely different types of systems for iron acquisition. Both contain unexpectedly large numbers of pseudogenes and incomplete systems, suggesting that they are undergoing genome size reduction. Interestingly, all 5 outer-membrane receptors in Bba are lacking in Bex. The 2 organisms have similar numbers and types of peptide and amino acid uptake systems as well as protein and carbohydrate secretion systems. The differences observed correlate with and may account, in part, for the different lifestyles of these 2 bacterial predators.

Comparative genomics of the transportome of Ten Treponema species

“…Tbr possesses the most with twenty, while Tpal and Tpar have the fewest with two each. A predominance of the MOP superfamily members is unusual for most other bacteria studied [65,29,66].…”

The Transporter Classification Database (TCDB): 2021 update

“…We have carried out studies to identify transporters in many groups of pathogenic and probiotic bacteria. These include numerous pathogenic, symbiotic and free living species of spirochetes such as (a) Leptospira ( 14 ) and (b) Treponema ( 15 ), (c) species of Bdellovibrio that kill and eat other Gram-negative bacteria, either from within (intracellular) or from without (extracellular) the prey bacteria ( 16 ), (d) probiotic and pathogenic strains of Escherichia coli ( 17 ), and (e) probiotic and pathogenic Bacteroides species ( 18 ). In addition, we have ongoing projects on probiotic and pathogenic Lactobacillus species, seven species of sulfur reducing proteobacteria, four different phyla of the recently discovered ‘Candidatus Phylum Radiation’ (CPR) nanobacteria ( 19 , 20 ), and four phyla of the newly discovered Asgard archaeal superphylum, presumably the closest prokaryotic relatives of Eukarya ( 21 ).…”

A Riboflavin Transporter in <b><i>Bdellovibrio exovorous</i></b> JSS

“…These predators are ubiquitous in the environment and have been isolated from soil, compost, sewage, activated sludge, and marine and terrestrial waters [Davidov et al, 2006a;Davidov et al, 2006b;Jurkevitch, 2006]. The complete genome sequences of both Bdellovibrio species are available, and this has allowed comparative analyses of transport systems in these organisms [Heidari Tajabadi et al, 2017].…”