4-Methylcytosine distribution follows the power function in Geobacter sulfurreducens genome.

Single-molecule real-time DNA sequencing revealed that 4-methylcytosine (m4C) commonly exists in bacterial genomes. In this work, samples with different m4C methylation patterns were studied. Results reveal that m4C modification is a biochemical reaction with distance effect, and its distribution follows the power function in the positive, negative, and double strands of genomic DNA sequences of Geobacter sulfurreducens. Furthermore, the value of regression coefficient in the fitting formula for double strands was the sum of those in the fitting formulae for positive and negative strands. Meanwhile, the value of exponent coefficient was the average, implicating an interesting mathematical phenomenon about power function. Considering the potent role of m4C in gene expression and the present results being obtained from the same genomic DNA sequence, this work suggests that the patterns of m4C distribution may be served as a signal for G. sulfurreducens to rapidly identify the genes to respond to environmental stresses or signals. This study opens a new avenue to extend our knowledge about the modification mechanisms and the epigenetic information of m4C modification in prokaryotes.