6027
To investigate regulatory networks in Legionella pneumophila , the gene encoding the homolog of the Escherichia coli stress and stationary-phase sigma factor RpoS was identified by complementation of an E. coli rpoS mutation .
 RpoS, rpoS, Escherichia coli stress and stationary-phase sigma factor
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 RpoS, rpoS, Escherichia coli stress and stationary-phase sigma factor