1542
To identify the requisite bacterial ligands , studies with isogenic mutants of P. aeruginosa PAK lacking pili , flagella , and the RpoN sigma factor were undertaken.
 protein: RpoN sigma factor
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 protein: RpoN sigma factor