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SipB Secretion through SPI-1 TTSS Was Regulated by Its C-terminus and InvE Protein in Salmonella typhimurium UK1.

초록/요약

SipB, one of the Salmonella invasion proteins, is secreted by SPI-1 (Salmonella Pathogenicity Island-1) TTSS. The aim of this experiment is to analyze the secretion signal of SipB required for SPI-1 TTSS route. In contrast to known secretion pathway, SipB N-terminal residue (SipB 1-160 and SipB 1-300) were secreted by flagella TTSS. When C-terminal regions (300-593, 500-593) were add to the N-terminal residue, they were secreted by SPI-1 TTSS. To find out how SipB C-terminal region affect its secretion, various point mutation plasmids in C-terminal region were constructed. These mutant`s secretion level was lower than SipB wild type, however the secretion of point mutations within SipB full length did not changed. As InvE was known to affect effector secretion in S. typhimurium, it was tested that the secretion pattern with SipB 1-160, SipB 1-160 500-593 in invE mutant. SipB 1-160 500-593 in invE mutant was rarely secreted same as full length SipB. Although secretion level of SipB 1-160 was unaffected in invE mutant, secretion route was changed from flagellar to SPI-1 TTSS. Taken together, it suggested that SipB C-terminal region and InvE protein are important to SPI-1 TTSS secretion.

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초록/요약

SipB는 Salmonella invasion protein중에 하나로서 SPI-1 TTSS로 분비된다. 이번 실험에서는 SipB가 SPI-1 TTSS 경로로 분비되기 위해 필요한 분비 신호를 분석하였다. 이미 알려진 분비경로와는 다르게, SipB 의 아미노 말단은 flagella TTSS로 분비되었다. (SipB 1-160 SipB 1-300). 하지만 이 아미노 말단부분에 카르복시 부분이 (300-593, 500-593) 더해지면 SPI-1 TTSS로 분비되었다. SipB 의 카르복시 말단 부위가 분비에 어떤 영향을 미치는지 알아보기 위하여, SipB 1-160 500-593의 카르복시 말단 부분에 점 돌연변이를 만들었다. 이 돌연변이의 분비 정도는 SipB의 야생형보다 줄어들었으나, 점 돌연변이를 SipB 전체부분에 도입하였을 때는 분비에 변화가 없었다. 또한 SipB 1-160 500-593은 InvE가 없을 때 분비되지 않았지만 SipB 1-160은 InvE에 관계없이 분비되었다. 비록 invE 돌연변이에서 SipB 1-160의 분비 정도는 변화가 없었지만, 분비되는 경로는 flagella TTSS에서 SPI-1 TTSS로의 차이가 있었다. 이와 같은 결과들은, SipB의 C-terminal과 InvE는 SPI-1 TTSS로의 분비에 중요하다는 것을 의미한다.

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목차

Abstract
Introduction 1
Material and Methods 5
Bacterial strains, media and growth conditions 5
Plasmid construction 5
Preparation of bacterial cytosol proteins and culture supernatant proteins 6
Invasion assay 9
Single base substitutions of SipB recombinant plasmids 10
P22 transduction 10
Results 12
SipB C-terminal region is important to be secreted through SPI-1 TTSS 12
Analysis of the SipB C-terminal region 15
Analysis of coiled-coil domain in SipB C-terminus 18
Point mutation in full length SipB did not affect its secretion level 21
InvE regulated the SipB secretion 23
Discussion 26
References 30
Abstract in Korean 37
Acknowledgement 38

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