Sigma A recognition sites in the Bacillus subtilis genome

Area of Science:

• Microbiology
• Molecular Biology
• Bioinformatics

Background:

• Sigma(A) RNA polymerase recognizes promoter DNA sequences to initiate transcription in bacteria.
• Promoter recognition involves specific DNA motifs, including the -10 region, which can have common or extended forms.
• Understanding these recognition sites is crucial for deciphering gene regulation.

Purpose of the Study:

• To develop a hidden Markov model for sigma(A) RNA polymerase cofactor recognition sites in Bacillus subtilis.
• To investigate the prevalence and characteristics of common versus extended -10 motifs.
• To identify novel promoter sites and their associated genes within the B. subtilis genome.

Main Methods:

• Construction of a hidden Markov model based on experimentally verified sigma(A) recognition sites.
• Genome-wide analysis of the Bacillus subtilis genome using the developed model.
• Site-directed mutagenesis to confirm gene expression dependency on identified promoter motifs.

Main Results:

• The model suggests greater information content at transcription initiation sites than previously recognized.
• Approximately half of the predicted sigma(A) recognition sites in the B. subtilis genome contain extended -10 motifs.
• Several response-regulator aspartate phosphatases, including rapA and rapB, were identified as depending on extended -10 promoter elements for expression.

Conclusions:

• The hidden Markov model provides a powerful tool for identifying bacterial promoter elements.
• Extended -10 motifs are a significant feature of sigma(A) promoter recognition in Bacillus subtilis.
• The findings reveal new insights into the regulation of genes involved in cellular signaling pathways.