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.Dipicolinic acid (pyridine-2,6-dicarboxylic acid or PDC and DPA) is a
chemical compound which composes 5% to 15% of the dry weight
of bacterial spores.
2.It is implicated as responsible for the heat resistance of the endospore.
3.Prevent dehydration of water because DPA & Ca ions forms complex
with the water molecule.

3. Figure: Dipicolinic acid (DPA).
(a) Structure of DPA.
(b) (b) How Ca2+ cross-links DPA molecules to form a complex

4. 4. The heat resistance of macromolecules within the core increases.
5. Calcium-dipicolinic acid complex also functions to protect DNA from
heat denaturation by inserting itself between the nucleobases, thereby
increasing the stability of DNA.
6. The core is the spore protoplast. It contains a complete nucleus
(chromosome), all of the components of the protein-synthesizing
apparatus, and an energy-generating system based on glycolysis. A
number of unique enzymes are formed (eg, dipicolinic acid synthetase).

5. Significance of small acid-soluble proteins (SASPs):
1.Spores of Bacillus subtilis contain a number of small, acid-soluble spore
proteins (SASP) which comprise up to 20% of total spore core protein.
2.The endospore core contains high levels of small acid-soluble proteins
(SASPs). These proteins are made during the sporulation process and have at
least two functions.
3.SASPs bind tightly to DNA in the core and protect it from potential damage
from ultraviolet radiation, desiccation, and dry heat.

6. 4. Ultraviolet resistance is conferred when SASPs change the molecular
structure of DNA from the normal “B” form to the more compact “A” form. A-
form DNA better resists pyrimidine dimer formation by UV radiation, a means
of mutation.
5. Resists the denaturing effects of dry heat.
6.In addition, SASPs function as a carbon and energy source for the outgrowth
of a new vegetative cell from the endospore during germination.
Ref: www. Google.com

7. Thank you…!