Lowland and Highland Deer Mice Hemoglobin
Serena Shyu, Hannah Lara, Pang Chang, Trisha Xiong
Faculty Mentor: Dr. Colleen Conway, Dr. Kathleen Boyle, & Dr. Maureen Leonard
STORY
The LA deer mouse hemoglobin showed a lowered oxygen affinity which is explained by the the movement of E helix as it has a more mobile alpha helix. The reason HA deer mice hemoglobin has higher oxygen affinity may be due to the steric hindrance to oxygen binding to chloride ions and 2,3-diphosphoglycerate (DPG). Some main amino acid mutations are in the 60th, 64th, and 71st position of the alpha subunit. These substitutions affect the function of the molecule’s structure by α1β2/α2β1 subunit by increasing the hemoglobin’s oxygen affinity in a highland deer mice compared to a lowland deer mice.
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ABSTRACT
Deer mice can live at a high altitude (HA) or at a low altitude (LA), since they are native to those environments. LA deer mice can survive at a low oxygen affinity level due to its E-helix structure, but a HA deer mice cannot. A HA deer mice needs a higher oxygen affinity level which may be explained by the steric hindrance to 2,3-diphosphoglycerate (DPG), and chloride ions to survive. The altitude levels between these two have mutational changes which affects the oxygen affinity to increase in a HA deer mice. This was determined by comparing both HA with LA from their proteins being purified, crystallized, and experimented with UV-visible spectrometry.
INTRODUCTION
The lowland deer mice functions at a low altitude, thus less oxygen is needed. The highland deer mice functions at a high altitude, thus more oxygen is needed. These molecules are important to the deer mice’s ecology and evolution as the altitude affects the environment.
HOW DO WE KNOW?
The lowland and highland deer mice structures were identified by their proteins purified, crystallized, and by UV-visible spectrometry to view the structures. The function was identified by a superimposable program called PyMOL to find the structural differences in the folding on His45 and the residues around the active site or nearby and the key residues and helices in the α unit. The structure-function were connected and identified by comparing the lowland and the highland deer mice structures with each other and seeing the interaction of how the amino acids interacted with the function using a PISA web server with amino acid changes between them due to steric hindrance and chloride ion.
WHAT’S THE NEXT QUESTION?
What structural mechanisms is responsible for the unusual patterns of allosteric regulation of the steric hindrance of DPG and chloride ion?
ACKNOWLEDGMENTS
This project was supported by the National Science Foundation under NSF S-STEM grant 1644003. We also give acknowledgements to Dr. Cheryl Bailey.
REFERENCES
Highland Deer Mice
Lowland Deer Mice (4H2L)
Highland Deer Mice (5KER)
Lowland Deer Mice