Difference between revisions of "Part:BBa K2788000"

Latest revision as of 23:20, 16 October 2018

HsbA_Beauveria bassiana ARSEF 2860.

Hydrophobic Surface Binding Protein A is called for short HsbA. It forms a protective layer on the surface of the bacteria to form an aerial structure, reducing the surface hydrophobic pressure and promoting the interaction between the fungus and the host. In our project, HsbA protein helps our fungus stick more firmly to the body surface of cockroach and makes infection more effectively.

Sequence and Features

iGEM2018 SZU-China

The HsbA from Beauveria bassiana encodes a kind of membrane surface hydrophobic protein which helps our spores adhere to the wax on the cockroach body surface. Moreover, with the overexpression of HsbA, our spores can more effectively adhere to the cockroach. Then it will follow as spores’ germination, germinal tube, appressorium and the next penetrating process.

This part was inserted into the expression vector by restriction sites EcoRI and PstI (Fig.1), and the correct construction of this recombinant plasmid was confirmed by PCR identification and sequencing of the PCR products.

Fig.1 Construction of expression vector HsbA-pBC. PgpdA and TtrpC come from parts of 2016_NYMU-Taipei: BBa_K2040101 and BBa_K2040102, and HsbA comes from the Beauveria bassiana ARSEF 2860. The PgpdA-HsbA-TtrpC part is connected to the pBC plasmid through the BioBrick site.

We transformed the expression vectors into Metarhizium anisopliae 128 by the method of Xiaoling Wang, and the positive clone was confirmed by G418 sulfate screening and nucleic acid electrophoresis.(Fig.2)

Fig.2 0.8%Agarose Gel Electrophoresis of DNA extracted from the positive clones and its validated by PCR. The product of plasmid digested showed two signal bands at 335 bp and 741bp respectively, which correspond to the length of M.a primer PCR product and HsbA primer PCR product. Lane 1: M.a primer PCR product; Lane 2: HsbA primer PCR product; Lane M: DL marker.

The transformed strain Metarhizium anisopliae 128 was grown in 1/4 SDAY liquid medium, and obtain total protein by FastPrep and ultrasonic crushing. The lysate was then centrifuged and the supernate was electrophoresed on a sodium dodecyl sulfate(SDS)-12% (wt/vol) polyacrylamide gel, followed by Coomassie blue staining.(Fig.3)

Fig.3 SDS-PAGE analysis of membrane protein of wild-type Metarhizium anisopliae 128 and modified Metarhizium anisopliae 128. Lane M: Marker Ladder；Lane 128：Metarhizium anisopliae 128；Lane HsbA1 and HsbA2: recombinant strain Metarhizium anisopliae 128. Lane HsbA1 and HsbA2 showed the same band(in red box) corresponded with the molecular weight of HsbA(24kDa).

Besides, by using the method of compared four areas of each wing in the scanning electron microscope before and after treatment which is ‘put the petri dishes on WD-9405B horizontal shaking table and opened the lowest rolling speed for 10min (to make the spores on the wings evenly impacted by the water flow)’ in the HsbA macro verification protocol, we can finally compared whether there was any change in the position and number of spores in the observing area. (illustrated with Fig.4 and Fig.5)

Fig.4 One of the wild-type Metarhizium anisopliae 128 groups: P1 is the picture before treated and P2 is the picture after treated. The spores quantity is 40 in P1 and 102 in P2. And there are only two left that have not been washed away and moved. The adherence rate is 2/40=5.0%

It’s obvious that it happens great change（circle in red）in the position and number of spores in the observing area of wild-type Metarhizium anisopliae 128 experimental groups.

Fig.5 One of the Metarhizium anisopliae HsbA transformant groups: P3 is the picture before treated and P4 is the picture after treated. The spores quantity is 42 in P3 and 52 in P4. And there are 41 spores left that have not been washed away and moved. The adherence rate is 41/42=97.6%

It’s obvious that it almost happens no change except the place (circled in red) in the position and number of spores in the observing area of Metarhizium anisopliae HsbA transformant experimental groups.

Finally, the following chart (Fig.6) can be obtained by statistical data of four areas in all experimental groups.

Fig.6 M.a128 is the wild-type Metarhizium anisopliae 128 groups, and the adherence rate in average is 26.7%. HsbA is the Metarhizium anisopliae 128 HsbA transformant groups, and the adherence rate in average is 97.7%.

In conclusion, this result well confirmed that Metarhizium anisopliae HsbA transformant certainly enhanced the capacity of adhesion.