Yersinia pestis is a bacterium that causes plague. It is transmitted to humans primarily through the bites of infected fleas from rodents. The bacterium is able to form biofilms in the flea gut and block its digestion, making it hungry and more likely to bite and transmit the pathogen. Key to Y. pestis' ability to cause disease is forming colonies and biofilms, which involves regulating genes through the cyclic-di-GMP second messenger molecule and a complex interplay between the hmsHFRS, Rcs and other gene operons.

1. Yersinia pestis infection
A regulatory perspective
‫یگانه‬ ‫امید‬
‫میکروبیولوژی‬ ‫دکتری‬
1
By: Omid Yeganeh

2. •‫یرسینیا‬،،‫منفی‬ ‫گرم‬ ‫های‬ ‫باسیل‬،‫ی‬‫اختیار‬ ‫ی‬‫هواز‬‫بی‬‫مهم‬ ‫های‬ ‫جنس‬ ‫از‬ ‫و‬ ‫متحرک‬‫غیر‬
‫هستند‬‫انتروباکتریاسه‬ ‫خانواده‬.‫ب‬ ،‫انسان‬ ‫در‬ ‫یرسینیا‬ ‫های‬ ‫گونه‬ ‫از‬ ‫برخی‬‫هستند‬ ‫ا‬‫ز‬‫ی‬‫ر‬‫یما‬
‫مانند‬‫پستیس‬ ‫یرسینیا‬‫عامل‬ ‫که‬‫ن‬‫طاعو‬ ‫ی‬‫بیمار‬(plague)‫است‬.
2

3. ‫کند‬‫می‬ ‫سرایت‬ ‫انسان‬ ‫به‬ ،‫مبتال‬ ‫موش‬ ‫بدن‬ ‫ککهای‬ ‫راه‬ ‫از‬ ً‫ا‬‫غالب‬ ،‫طاعون‬ ‫بیماری‬.
•Y.pestis‫ش‬‫می‬ ‫آن‬ ‫شدن‬ ‫بسته‬ ‫باعث‬ ،‫کک‬ ‫ی‬‫مر‬ ‫ای‬‫ر‬‫مج‬ ‫در‬ ‫بیوفیلم‬ ‫تشکیل‬ ‫با‬‫و‬ ‫ود‬
‫بزند‬ ‫نیش‬ ‫بیشتر‬ ‫خود‬ ‫گرسنگی‬‫فع‬‫ر‬ ‫ای‬‫ر‬‫ب‬ ‫تا‬ ‫شود‬‫می‬‫ر‬‫مجبو‬ ‫گرسنه‬ ‫کک‬.‫ک‬
ً
‫معموال‬ ‫ها‬‫ک‬
‫به‬‫خصوص‬ ‫به‬ ،‫جوندگان‬‫ها‬ ‫موش‬‫ای‬ ‫تعداد‬ ‫که‬ ‫تی‬‫ر‬‫صو‬‫ر‬‫د‬ ‫ولی‬ ،‫کنند‬‫می‬‫حمله‬‫ن‬
‫می‬ ‫ا‬‫ر‬ ‫انسان‬ ‫جمله‬ ‫از‬ ‫ی‬‫دیگر‬ ‫ر‬‫جانو‬ ،‫شود‬ ‫کم‬ ‫ن‬‫طاعو‬ ‫به‬ ‫ابتال‬ ‫علت‬ ‫به‬ ‫ان‬‫ر‬‫جانو‬‫زبان‬
‫دهند‬‫می‬ ‫ار‬‫ر‬‫ق‬.
3

4. ‫است‬ ‫بوده‬‫مهم‬ ‫بسیار‬ ‫یخ‬‫ر‬‫تا‬ ‫ل‬‫طو‬‫در‬ ‫ن‬‫طاعو‬ ‫گ‬‫ر‬‫بز‬ ‫های‬‫ی‬‫گیر‬‫همه‬‫شیوع‬ ‫در‬ ‫ها‬‫موش‬ ‫نقش‬.
4

5. ‫یرسینیا‬ ‫عفونت‬ ‫انتقال‬ ‫های‬‫اه‬‫ر‬
•‫ن‬‫خو‬ ‫طریق‬‫از‬:‫انسان‬ ‫به‬ ‫کنه‬ ‫نیش‬‫از‬ ‫پستیس‬ ‫یرسینیا‬‫انتقال‬‫مثل‬.
•‫مستقیم‬ ‫تنفس‬ ‫طریق‬‫از‬:‫آل‬ ‫های‬‫لباس‬ ،‫مایعات‬ ‫با‬ ‫تماس‬‫اه‬‫ر‬‫از‬‫پستیس‬‫یرسینیا‬‫انتقال‬،‫ی‬‫باکتر‬ ‫به‬ ‫وده‬
‫ان‬‫ر‬‫بیما‬‫سرفه‬ ‫یا‬‫عطسه‬ ،‫هوا‬‫در‬ ‫معلق‬ ‫ات‬‫ر‬‫قط‬‫تنفس‬.
•‫اما‬ ،‫است‬ ‫نادر‬ ‫خیارکی‬ ‫ن‬‫طاعو‬ ‫به‬ ‫نسبت‬ ‫اینکه‬ ‫با‬‫پستیس‬‫یرسینیا‬‫از‬ ‫ی‬ ‫ناش‬ ‫ی‬‫یو‬‫ر‬ ‫ن‬‫طاعو‬‫شدت‬ ‫به‬
‫است‬ ‫تر‬‫کشنده‬ ‫اتب‬‫ر‬‫م‬ ‫به‬ ‫و‬‫ی‬‫مسر‬.
5

6. •‫طریق‬‫از‬ ‫ابتدا‬‫یرسینیا‬ ‫ی‬‫باکتر‬ ‫اینکه‬ ‫د‬‫ر‬‫مو‬‫در‬ ‫هایی‬ ‫بحث‬‫وآ‬‫ز‬‫تو‬‫و‬‫پر‬‫پید‬‫انتقال‬ ‫کک‬ ‫به‬‫وجود‬ ،‫کند‬ ‫می‬ ‫ا‬
‫است‬‫ی‬‫اختیار‬‫سلولی‬ ‫داخل‬ ‫انگل‬‫عنوان‬ ‫به‬‫یرسینیا‬ ‫ی‬‫باکتر‬ ‫ا‬‫ر‬‫ی‬‫ز‬‫د‬‫ر‬‫دا‬.‫ش‬ ،‫دلیل‬ ‫همین‬ ‫به‬‫طریق‬‫از‬ ‫اید‬
‫کند‬ ‫پیدا‬‫انتقال‬ ‫کک‬ ‫به‬ ‫ها‬ ‫آمیب‬.
6

7. •‫ایی‬‫ز‬‫ی‬‫ر‬‫بیما‬ ‫در‬ ‫موثر‬ ‫های‬‫ر‬‫فاکتو‬ ‫از‬ ‫یکی‬‫پستیس‬‫یرسینیا‬:‫ن‬‫اسیو‬‫ز‬‫کلونی‬‫تشکیل‬ ‫و‬
‫بیوفیلم‬‫کک‬ ‫پشه‬ ‫ش‬‫ر‬‫گوا‬ ‫ای‬‫ر‬‫مج‬ ‫در‬(flea)‫است‬.
7

8. •‫تشکیل‬‫بیوفیلم‬‫توسط‬hmsHFRS operon‫گردد‬‫می‬ ‫تنظیم‬‫مثبت‬ ‫ر‬‫بطو‬.
8

9. •‫های‬ ‫ن‬‫ژ‬hmsHFRS operon‫آنزیم‬ ‫ی‬ ‫کننده‬ ‫بیان‬‫دی‬-‫سیکالز‬ ‫گوانیالت‬‫اس‬‫ت‬.
•‫ر‬‫کوفاکتو‬ ‫تولید‬ ‫به‬ ‫منجر‬ ‫آنزیم‬ ‫این‬cyclic-di-GMP‫شود‬ ‫می‬.
9
Diguanylate cyclase enzyme
cyclic-di-GMP

10. •cyclic-di-GMP‫یدها‬‫ر‬‫ساکا‬ ‫پلی‬‫و‬‫اگز‬ ‫و‬ ‫چسبنده‬ ‫های‬ ‫تئین‬‫و‬‫پر‬ ‫تولید‬ ‫در‬EPS
‫با‬ ‫توسط‬ ‫بیوفیلم‬ ‫تشکیل‬ ‫و‬ ‫ن‬‫اسیو‬‫ز‬‫کلونی‬‫به‬ ‫منجر‬ ‫امر‬ ‫این‬ ‫که‬ ‫د‬‫ر‬‫دا‬ ‫نقش‬‫می‬ ‫ها‬ ‫ی‬‫کتر‬
‫شود‬.
10

11. 11
‫همچنین‬cyclic-di-GMP‫در‬‫ر‬‫کوفاکتو‬‫بعنوان‬:
‫به‬‫مربوط‬‫های‬‫ن‬‫ژ‬‫بیان‬motility
‫ا‬‫ز‬‫ی‬‫ر‬‫بیما‬‫های‬‫ن‬‫ژ‬‫بیان‬virulence
‫ل‬‫سلو‬‫چرخه‬‫و‬‫ی‬‫ساز‬‫همانند‬cell cycle

12. •‫های‬ ‫ن‬‫ژ‬ ،‫بیوفیلم‬ ‫تشکیل‬ ‫عدم‬ ‫جهت‬Rcs operon‫کنند‬‫می‬ ‫عمل‬.
•‫ن‬‫و‬‫اپر‬ ‫واقع‬ ‫در‬Rcs‫کننده‬ ‫تنظیم‬ ‫یک‬‫منفی‬‫بیوفیلم‬ ‫و‬ ‫ن‬‫اسیو‬‫ز‬‫کلونی‬ ‫ای‬‫ر‬‫ب‬‫می‬ ‫شمار‬ ‫به‬
‫د‬‫و‬‫ر‬.
12

13. •‫محصوالت‬Rcs operon‫ن‬‫و‬‫اپر‬ ‫های‬‫ن‬‫ژ‬ ‫از‬‫ی‬ ‫نویس‬‫و‬‫ر‬ ‫مهار‬ ‫با‬
hmsHFRS‫بیوف‬‫تشکیل‬ ‫عدم‬ ‫یا‬ ‫بیوفیلم‬‫توسعه‬ ‫عدم‬ ‫به‬ ‫منجر‬‫یلم‬
‫دی‬ ‫آنزیم‬ ‫سنتز‬ ‫مهار‬ ‫بوسیله‬-‫شوند‬ ‫می‬ ‫سیکالز‬ ‫گوانیالت‬.
•‫ب‬ ‫سیگنال‬ ‫یک‬ ، ‫باکتریها‬‫تعداد‬ ‫ایش‬‫ز‬‫اف‬‫و‬ ‫بیوفیلم‬‫توسعه‬ ‫با‬‫ن‬‫و‬‫در‬ ‫ه‬
‫ا‬‫ی‬ ‫نویس‬‫و‬‫ر‬ ‫تقویت‬ ‫موجب‬‫و‬ ‫شود‬ ‫می‬‫مخابره‬ ‫ی‬‫باکتر‬ ‫سیتوپالسم‬‫نهای‬‫ژ‬ ‫ز‬
‫ن‬‫و‬‫اپر‬Rcs‫های‬ ‫تئین‬‫و‬‫پر‬ ‫غلظت‬ ‫فتن‬‫ر‬ ‫باال‬ ‫و‬RcsA‫و‬Rcs B‫شود‬ ‫می‬.
•‫تئین‬‫و‬‫پر‬Rcs B‫به‬‫ا‬‫ر‬‫خود‬ ‫فسفر‬ ‫و‬ ‫شود‬ ‫می‬ ‫فسفریله‬ ‫اتو‬ ‫ابتدا‬Rcs A
‫شدن‬ ‫فعال‬ ‫موجب‬ ‫و‬ ‫دهد‬ ‫می‬ ‫انتقال‬Rcs A‫شود‬ ‫می‬.
13

14. •Rcs A‫یا‬ ‫شده‬ ‫فسفریله‬(‫شده‬ ‫فعال‬)‫من‬ ‫کننده‬ ‫تنظیم‬ ‫عنوان‬‫به‬ ،‫بر‬ ‫فی‬
‫ن‬‫و‬‫اپر‬‫به‬ ‫مربوط‬ ‫ر‬‫اتو‬‫ر‬‫اپ‬‫ی‬‫و‬‫ر‬hmsHFRS‫ی‬‫گیر‬ ‫ار‬‫ر‬‫ق‬ ‫مانع‬‫و‬ ‫گرفته‬ ‫ار‬‫ر‬‫ق‬
‫آنزیم‬ ‫صحیح‬RNA-‫مربوط‬ ‫نهای‬‫ژ‬ ‫از‬‫ی‬ ‫نویس‬‫و‬‫ر‬ ‫مانع‬ ‫نتیجه‬ ‫در‬ ‫و‬ ‫از‬‫ر‬‫پلیم‬‫به‬
‫ن‬‫و‬‫اپر‬hmsHFRS‫گردد‬ ‫می‬.
•‫دی‬ ‫آنزیم‬ ،‫آن‬ ‫دنبال‬ ‫به‬-‫کوف‬ ‫و‬ ‫شود‬ ‫نمی‬ ‫سنتز‬ ،‫سیکالز‬ ‫گوانیالت‬‫ر‬‫اکتو‬
cyclic-di-GMP‫تش‬ ‫یا‬‫توسعه‬ ‫مهار‬ ‫به‬ ‫منجر‬ ‫و‬ ‫شود‬ ‫نمی‬ ‫ساخته‬ ‫نیز‬‫کیل‬
‫شود‬ ‫می‬ ‫بیوفیلم‬.
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15. Small Non-Coding RNAs (sRNAs): a Mechanism of
Post-Transcriptional Regulation
• These are small molecules of RNA that are not
translated into proteins.
• In general these molecules carry out their
regulatory function by base-pairing to a limited
complementary sequence in the mRNAs of their
cognate target gene.
• This interaction leads to modification of mRNA
translation, thereby influencing the target gene
expression and protein activity.
15

16. • These sRNAs usually bind to the Shine-Dalgarno (SD)
sequence of the mRNA thereby occluding the ribosome-
binding site (RBS), or bind to the coding region of the
mRNA. Both base-pairing interactions result in inhibition
of translation, and can be coupled with enhanced
RNAse activity that facilitates increased rate of mRNA
cleavage and degradation.
16
Shine-Dalgarno (SD) sequence is a site in bacterial and archaeal messenger RNA,
generally located around 8 bases upstream of the start codon AUG.

17. • The loose base-pairing interaction between the trans-encoded
sRNA and target mRNA is often stabilized by an RNA-chaperone
protein like Hfq.
• Besides the sRNA-mRNA interaction, sRNAs can directly interact
with regulatory proteins to interfere with their function.
17

18. 18

19. • Four Small non-coding RNAs (sRNAs) has been
detected in Yersinia pestis as key molecules that
may provide expression of appropriate disease
enabling factors :
Yp-sR1, Yp-sR2, Yp-sR16 and Yp-sR38
19

20. SsrA-SmpB system in Y.pestis
• This system in Y.pestis consists of : 10s Small
stable RNAA (SsrA) and small protein B
(SmpB) are components of a unique bacterial
translational control system.
• This system is important for maintaining cellular
homeostasis and bacterial survival in adverse
conditions, and as such may be advantageous for
efficient response to adverse infection conditions.
20

21. • The SsrA-SmpB system helps maintain the bacterial translational
machinery in a fully operational state by dealing with ribosomes that
are stalled on defective mRNAs that lack stop codons.
21

22. • SsrA RNA functions both as a tRNA and mRNA.
• SmpB is essential for recognition and delivery of
SsrA to target stalled ribosomes.
• SmpB binds specifically to the tRNA-like domain
of SsrA and thus stabilizes SsrA tertiary structure.
22

23. • In Y. pestis, a smpB-ssrA mutant is Avirulent to
mice.
• This mutant exhibits as lower growth rate at 37◦C.
• Inagreement ,the transcriptional level of SsrA is
higher at 37◦C than at 26◦C in Y. pestis , which
may help Y. pestis adapt to natural temperature
alterations during its transmission from fleas to
mammals.
23

24. • Most significantly, it has been demonstrated that
intranasal vaccination of mice with the SsrA mutant
induced a strong IgG antibody response, and vaccinated
animals were well protected against pulmonary Y. pestis
infection.
• Taken together, these characteristics present this mutant
strain as a favorable candidate for a live attenuated cell-
based vaccine against pneumonic plague.
24

25. Oxidative Stress Response in Y. pestis
• Reactive oxidative produced by the flea upon infection,
is a known stress that Y. pestis has to defend itself against
during the early stages of infection.
•
25

26. • GPX and GST are two stress response proteins
participate in protecting Y.pestis against the
damage of oxidative stress.
26

27. Conclusion
• In the last decade, research on sRNA identification and functional
analysis has begun to reveal a previously hidden regulatory layer in
the already complex gene networks that control cellular function
and behavior.
27

28. • It has been shown that small RNA act as regulators of Yersinia
virulence and host adaptation.
• sRNAs coordinate metabolic adaptation to enhance the host–
pathogen interaction.
28

29. • Many fundamental questions about sRNA biology remain to be
answered.
• Studies identifying, validating and functionally charactering the
roles of sRNAs in the various biologically relevant host tissues may
prove to be useful in determining the host-specific and niche
dependent regulatory mechanisms crucial
29

30. • Because experimental efforts to determine cellular function of
sRNAs are time-consuming and labor-intensive, and bioinformatics
prediction of target mRNAs remains largely unreliable being
confounded by imperfect complementarity between the sRNA and
mRNA, researchers are faced with several challenges in the field of
sRNA biology.
30

31. • The mechanisms of sRNA regulation suggests the possibility that inhibition
of key sRNA folding or targeted mRNA interactions strategies can be
developed as the basis of novel anti-infective strategies, especially in the
face of antibiotic resistance.
31

32. 32