Functional insight from the tetratricopeptide repeat-like motifs of the type III secretion chaperone SicA in Salmonella enterica serovar Typhimurium.
SicA functions both as a class II chaperone for SipB and SipC of the type III secretion system (T3SS)-1 and as a transcriptional cofactor for the AraC-type transcription factor InvF in Salmonella enterica subsp. enterica serovar Typhimurium. Bioinformatic analysis has predicted that SicA possesses three tetratricopeptide repeat (TPR)-like motifs, which are important for protein-protein interactions and serve as multiprotein complex mediators. To investigate whether the TPR-like motifs in SicA are critical for its transcriptional cofactor function, the canonical residues in these motifs were mutated to glutamate (SicAA44E , SicAA78E , and SicAG112E ). None of these mutants except SicAA44E were able to activate the expression of the sipB and sigD genes. SicAA44E still has a capacity to interact with InvF in vitro, and despite its instability in cell, it could activate the sigDE operon. This suggests that TPR motifs are important for the transcriptional cofactor function of the SicA chaperone.
School of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
Jin Seok
JS
Kim
Bae-Hoon
BH
Kim
Jung Im
JI
Jang
Jeong Seon
JS
Eom
Hyeon Guk
HG
Kim
Iel Soo
IS
Bang
Yong Keun
YK
Park
D020816:Amino Acid Motifs / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics / Q000502:physiology; D055550:Protein Stability; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology
D001426:Bacterial Proteins; D018832:Molecular Chaperones; C094577:SicA protein, Salmonella typhimurium
Salmonella pathogenicity island 1; secretion; transcription regulation