Stay or Go: Sulfolobales Biofilm Dispersal is Dependent on a Bifunctional VapB Antitoxin

ABSTRACT: A Type II VapB14 Antitoxin regulates biofilm dispersal in the archaeal thermoacidophile Sulfolobus acidocaldarius, not only through traditional Toxin neutralization but also through noncanonical transcriptional regulation. Type II VapC Toxins are ribonucleases that are neutralized by their proteinaceous cognate Type II VapB Antitoxin. VapB Antitoxins have a flexible tail at their C-terminus that covers the Toxin’s active site neutralizing its activity. VapB Antitoxins also have a DNA binding domain at their N-terminus that allows them to not only auto-repress their own promoters but also distal targets. VapB14 Antitoxin gene deletion in S. acidocaldarius stunted biofilm and planktonic growth and increased motility structures (archaella). Conversely, planktonic cells were devoid of archaella in the ΔvapC14 cognate Toxin mutant. VapB14 is highly conserved at both the nucleotide and amino acid levels across the Sulfolobales, extremely unusual for Type II Antitoxins that are typically acquired through horizontal gene transfer. Furthermore, homologs of VapB14 are found across the Crenarchaeota, in some Euryarchaeota, and even bacteria. S. acidocaldarius vapB14 and its homolog in the thermoacidophile Metallosphaera sedula (Msed_0871) were both up-regulated in biofilm cells, supporting the role of the Antitoxin in biofilm regulation. The findings here suggest that a stand-alone VapB-type Antitoxin was the product of selective evolutionary pressure to influence biofilm formation in these archaea, a vital microbial community behavior.

ORGANISM(S): Sulfolobus acidocaldarius Sulfolobus acidocaldarius DSM 639

PROVIDER: GSE226483 | GEO | 2023/03/27

REPOSITORIES: GEO