Page 13 - U. Protein structure and function

Structural analysis of fungal pathogenicity-related
casein kinase α subunit, Cka1, in the human fungal

pathogen Cryptococcus neoformans

1
Belinda X. Ong , Youngki Yoo , Myeong Gil Han , Jun Bae Park , Myung Kyung Choi , Yeseul
1
2
1
1
2
3
3
Choi , Jeon-Soo Shin , Yong-Sun Bahn & Hyun-Soo Cho 1
Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
Department of Microbiology, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
Research background

Figure 5. Measurement of the half maximal inhibitory
concentration (IC50) of CX-4945 for hsCK2α and
cnCka1 through in vitro kinase assay. (a) hsCK2α
results. (b) cnCka1 results.
- Cryptococcus neoformans is one of human
pathogenic fungi.
- More than a million infections and more than
600,000 deaths annually.
- Nevertheless, there are no appropriate treatments.

Figure 2. Overall structure of cnCka1-CX-4945. (a)
Structure of cnCka1-CX-4945. (b) Electrostatic potential
map. (c) 2Fo-Fc map showing the binding of CX-4945 at
the ATP-binding site contoured 2.0σ. (d) Interactions
between cnCka1 residues and CX-4945.

- Recent study of Bahn’s lab. have found the
essential kinase of Cryptococcus neoformans
through a large scale kinase knock-out assay.
- Among them, when the knock-out of Cka1 protein
kinase(casein kinase 2 family) was knocked-out,
cell growth was dramatically decreased.
Figure 6. Deviations in protein-inhibitor interactions
when CX-4945 is bound. Superimposition of the
Results cnCka1-CX-4945 and hsCK2α-CX-4945 structures
showing the residues around the catalytic cleft. (a)
Interactions of His159, (b) Arg46 and (c) Thr112 with
CX-4945

Conclusion
2+
1. We report the structures of cnCka1-AMPPNP-Mg (2.40 Å)
and cnCka1-CX-4945 (2.09 Å).
2. This may explain for the difference in binding affinities and
protein-inhibitor interactions between cnCka1-CX-4945 and
Figure 3. Structural comparisons among Ck2α hsCK2α-CX-4945.
orthologues: cnCka1, zmCK2α, hsCK2α, pfCK2α. (a)
Superimposition of cnCka1-AMPPNP-Mg 2+ and zmCka1- 3. This finding suggests a possibility that CX-4945 could be
AMPPNP-Mg 2+ of catalytic sites. (b) Structural deviations further chemically modified for optimally inhibiting cnCka1
at the N-lobe of cnCka1, zmCK2α, hsCK2α, pfCK2α. activity based on its structural information presented by this
study.
4. This potential CX-4945 derivative optimized for cnCka1
could have a good anti-cryptococcal activity with a
reasonable therapeutic index.
Figure 1. Overall structure of cnCka1-AMPPNP-Mg .
2+
(a) Structure of cnCka1-AMPPNP-Mg . (b)
2+
Electrostatic potential map. (c) 2Fo-Fc map showing
the binding of AMPPNP-Mg at the ATP-binding site Reference
2+
contoured 2.0σ. (d) Interactions between cnCka1
residues and AMPPNP-Mg 2+ 1. Scientific Reports, (2019) 9:14398
Figure 4. Surface plasmon resonance sensorgrams
showing the interactions of hsCK2α and cnCka1 with the 2. Nat. comm. (2016) 7:12766
inhibitor CX-4945. (a) Interactions between hsCK2α and 3. Clin. Cancer Res. (2016) 22(12)
CX-4945. (b) Interactions between cnCka1 and CX-4945. 4. Neurotherapuetics (2011) 8, 103-116
5. Emerg. Infect Dis. (2010) 16(1), 14-20