The genome of ‘Ca. Liberibacter asiaticus’ encodes only three sigma subunit factors, which enable differential transcription of genes by RNA polymerase (Table 2). These include one sigma 70 for genes expressed during exponential growth, one sigma 54 for genes involved in nitrogen metabolism and one sigma 32, involved in the heat shock or other stress responses. In contrast, the S. meliloti encodes 11 sigma factors, including three sigma 54 subunits and four sigma 24 subunits which enable expression of factors needed for the heat shock response as well as for factors exported from the cell. S. meliloti also has a special sigma factor, FecI for the expression of genes needed for the uptake of iron.
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There were errors in the first paragraph of the Sigma factors section of Results and Discussion. The correct text is: The genome of ‘Ca. Liberibacter asiaticus’ encodes only two sigma subunit factors, which enable differential transcription of genes by RNA polymerase (Table 2). These include one sigma 70 for genes expressed during exponential growth and one sigma 32, involved in the heat shock or other stress responses. 'Ca. Liberibacter asiaticus' also has putative sigma 54 dependent transcription regulator and a probable sigma 54 modulation protein (Table 2). In contrast, the S. meliloti encodes 11 sigma factors, including one sigma 54 subunit and four sigma 24 subunits which enable expression of factors needed for the heat shock response as well as for factors exported from the cell. S. meliloti also has a special sigma factor, FecI for the expression of genes needed for the uptake of iron.