Significance of DPA & SASPs

Significance of Dipicolinate (DPA) and small acid-soluble proteins (SASPs)

1. Significance of DPA & SASPs
Dr. Deepak U. Bhusare
Department of Microbiology
D. B. ACS College, Bhokar.

2. Significance of Dipicolinate (DPA):
1.Dipicolinicacid(pyridine-2,6-dicarboxylicacidorPDCandDPA)isa
chemicalcompoundwhichcomposes5%to15%ofthedryweight
ofbacterialspores.
2.Itisimplicatedasresponsiblefortheheatresistanceoftheendospore.
3.PreventdehydrationofwaterbecauseDPA&Caionsformscomplex
withthewatermolecule.

3. Figure:Dipicolinicacid(DPA).
(a)StructureofDPA.
(b)(b)HowCa
2+
cross-linksDPAmoleculestoformacomplex

4. 4.Theheatresistanceofmacromoleculeswithinthecoreincreases.
5.Calcium-dipicolinicacidcomplexalsofunctionstoprotectDNAfrom
heatdenaturationbyinsertingitselfbetweenthenucleobases,thereby
increasingthestabilityofDNA.
6.Thecoreisthesporeprotoplast.Itcontainsacompletenucleus
(chromosome),allofthecomponentsoftheprotein-synthesizing
apparatus,andanenergy-generatingsystembasedonglycolysis.A
numberofuniqueenzymesareformed(eg,dipicolinicacidsynthetase).

5. Significance of small acid-soluble proteins (SASPs):
1.SporesofBacillussubtiliscontainanumberofsmall,acid-solublespore
proteins(SASP)whichcompriseupto20%oftotalsporecoreprotein.
2.Theendosporecorecontainshighlevelsofsmallacid-solubleproteins
(SASPs).Theseproteinsaremadeduringthesporulationprocessandhaveat
leasttwofunctions.
3.SASPsbindtightlytoDNAinthecoreandprotectitfrompotentialdamage
fromultravioletradiation,desiccation,anddryheat.

6. 4.UltravioletresistanceisconferredwhenSASPschangethemolecular
structureofDNAfromthenormal“B”formtothemorecompact“A”form.A-
formDNAbetterresistspyrimidinedimerformationbyUVradiation,ameans
ofmutation.
5.Resiststhedenaturingeffectsofdryheat.
6.Inaddition,SASPsfunctionasacarbonandenergysourcefortheoutgrowth
ofanewvegetativecellfromtheendosporeduringgermination.
Ref: www. Google.com

7. Thank you…!