doctoral dissertation
Povzetek
Po Gramu pozitivne bakterije uporabljajo peptide (autoinduktorje, AI) za medcelično
komunikacijo, s katerimi lahko regulirajo številne prilagoditve na kritično celično gostoto
populacije (kvorum). Obstoječe teorije in raziskave predpostavljajo, da AI signali in
pripadajoči sistemi za zaznavanje kvoruma regulirajo sintezo javnih dobrin (npr.
zunajceličnih proteaz in komponent matriksa, ki povezuje celice v biofilmih). To teorijo
smo testirali tudi v okviru doktorske disertacije. Kot model smo uporabili komunikacijski
sistem bakterije Bacillus subtilis, ki temelji na signalnem peptidu ComX in je del
komunikacijskega sistema ComQXPA. Ta uravnava bakterijsko genetsko kompetenco in
proizvodnjo lipopeptidnega antibiotika surfaktina sorazmerno s celično gostoto.
Predpostavili smo, da imajo mutante, ki ne proizvajajo ComX, znižano proizvodnjo
zunajceličnih proteaz in komponent matriksa. Prav tako smo preiskovali razgradnjo
peptida ComX s strani zunajceličnih proteaz bakterije B. subtilis. Eksperimenti so potrdili
pozitivno vlogo signala ComX pri proizvodnji zunajceličnih proteaz in občutljivost
ComX za razgradnjo z zunajceličnimi proteazami, ki jih regulira. Vloga ComX pri sintezi
komponent matriksa je bila v nasprotju s testirano hipotezo. V plavajočem biofilmu
mutante ComX smo namreč izmerili višjo kumulativno izražanje promotorjev matriksa
(P epsA , P tapA ); višjo koncentracijo zunajceličnih polisaharidov in proteinov na plavajoči
biofilm, a tudi nižje izražanje sporulacijskega gena spoIIQ, nižje število spor in več celic
na plavajoči biofilm kot pri divjem tipu. Zaključili smo, da sistem ComQXPA služi
bakteriji kot »stikalo«, ki zmanjša energijski vložek bakterij v rast in razvoj biofilma in
zagotovi večji vložek energije v sporulacijo in druge zgoraj omenjene adaptacije.
Ključne besede
cell signaling;protease;quorum quenching;biofilms;degredative enzymes;quorum sensing;pellicles;sporulation;
Podatki
Jezik: |
Angleški jezik |
Leto izida: |
2019 |
Tipologija: |
2.08 - Doktorska disertacija |
Organizacija: |
UL BF - Biotehniška fakulteta |
Založnik: |
[M. Špacapan] |
UDK: |
602.3:579.852.11:579.22:579.25(043.3) |
COBISS: |
9334393
|
Št. ogledov: |
684 |
Št. prenosov: |
287 |
Ocena: |
0 (0 glasov) |
Metapodatki: |
|
Ostali podatki
Sekundarni jezik: |
Slovenski jezik |
Sekundarni naslov: |
Povezave med sintezo zunajceličnih proteaz, komponent matriksa in medcelično komunikacijo v biofilmu bakterije Bacillus subtilis |
Sekundarni povzetek: |
Gram-positive bacteria use peptides as auto-inducing (AI) signals to regulate adaptive
processes such as production of public goods (extracellular molecules that can be
shared by the community). ComX is an AI peptide, mostly known for its role in the
regulation of bacterial competence and surfactin production in Bacillus subtilis. These
two traits are regulated accordingly to the bacterial population size, thus classifying
ComX as a quorum sensing (QS) signal. We used this peptide-based AI system (the
ComQXPA system), as a model to explore the links between cell-cell communication,
exoprotease production and biofilm matrix production. The positive regulation of
public goods (e.g. biofilm matrix components and exoproteases) by AI molecules in
bacteria has been implied by several existing theories and experiments. In order to
further corroborate these assumptions, we tested two hypotheses, predicting that the
inactivation of the B. subtilis cell-cell communication system will have a negative
impact on the production of exoproteases and biofilm matrix components. We also
investigated the potential of ComX regulated proteases to degrade the ComX AI
peptide. Obtained results confirmed that ComX plays an important role in exoprotease
synthesis. Additionally, we confirmed that the ComX regulated exoproteases can
degrade this signaling peptide. However, we also observed that the ComQXPA QS
system slows down the overall production of biofilm matrix components and promotes
sporulation. The floating biofilms of ComX deficient mutants produce more matrix
components, more cells but less spores at an early stage of biofilm formation and
exhibit a more synchronous induction into sporulation at the later stage. These results
suggest that the ComQXPA QS system serves as a switch that down modulates
investment into growth and biofilm formation and assures early investment into
sporulation and aforementioned late growth adaptations. |
Sekundarne ključne besede: |
celično signaliziranje;proteaze;dušenje kvoruma;biofilm;razgradni encimi;zaznavanje kvoruma;plavajoči biofilm;sporulacija;Bacillus; |
Vrsta dela (COBISS): |
Doktorsko delo/naloga |
Študijski program: |
0 |
Konec prepovedi (OpenAIRE): |
1970-01-01 |
Komentar na gradivo: |
Univ. v Ljubljani, Biotehniška fak. |
Strani: |
XII, 99, [10] f. |
ID: |
11271318 |