beta globin and mutations alexandra childs and ryan edwards
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Beta Globin and Mutations
Alexandra Childs and Ryan Edwards
Beta Globin
• Chromosome position: 11p15.5• DNA nucleotides position: 5246696..5248301• To the left of this gene in HBD or Delta globin
and to the right of this gene is OR51v1 or Olfactory Receptor
HBB Location
• http://ghr.nlm.nih.gov/gene=HBB
Sequence of Beta Globin
Green: intronsRed: exonsBlue: Everything that is transcribed but non-coding
Mature mRNA and Translated protein Sequence
•Nucleotide Sequence (444 nt): ATGGTGCATCTGACTCCTGAGGAGAAGTCTGCCGTTACTGCCCTGTGGGGCAAGGTGAACGTGGATGAAGTTGGTGGTGAGGCCCTGGGCAGGCTGCTGGTGGTCTACCCTTGGACCCAGAGGTTCTTTGAGTCCTTTGGGGATCTGTCCACTCCTGATGCTGTTATGGGCAACCCTAAGGTGAAGGCTCATGGCAAGAAAGTGCTCGGTGCCTTTAGTGATGGCCTGGCTCACCTGGACAACCTCAAGGGCACCTTTGCCACACTGAGTGAGCTGCACTGTGACAAGCTGCACGTGGATCCTGAGAACTTCAGGCTCCTGGGCAACGTGCTGGTCTGTGTGCTGGCCCATCACTTTGGCAAAGAATTCACCCCACCAGTGCAGGCTGCCTATCAGAAAGTGGTGGCTGGTGTGGCTAATGCCCTGGCCCACAAGTATCACTAA
Translation (147 aa): MVHLTPEEKSAVTALWGKVNVDEVGGEALGRLLVVYPWTQRFFESFGDLSTPDAVMGNPKVKAHGKKVLGAFSDGLAHLDNLKGTFATLSELHCDKLHVDPENFRLLGNVLVCVLAHHFGKEFTPPVQAAYQKVVAGVANALAHKYH
Beta Globin Mutations
• Shepherd’s Bush• Hb Mainz• M Saskatoon• Thalassemia Mutation on the Initiation Codon
ATG to ATA• Hb Rocky Mountain
Shepherd’s Bush
Gly and Asp
Glycine Aspartic Acid
→
SB Mutated Sequence• Mutated Nucleotide Sequence (444 nt):
ATGGTGCATCTGACTCCTGAGGAGAAGTCTGCCGTTACTGCCCTGTGGGGCAAGGTGAACGTGGATGAAGTTGGTGGTGAGGCCCTGGGCAGGCTGCTGGTGGTCTACCCTTGGACCCAGAGGTTCTTTGAGTCCTTTGGGGATCTGTCCACTCCTGATGCTGTTATGGGCAACCCTAAGGTGAAGGCTCATGGCAAGAAAGTGCTCGGTGCCTTTAGTGATGACCTGGCTCACCTGGACAACCTCAAGGGCACCTTTGCCACACTGAGTGAGCTGCACTGTGACAAGCTGCACGTGGATCCTGAGAACTTCAGGCTCCTGGGCAACGTGCTGGTCTGTGTGCTGGCCCATCACTTTGGCAAAGAATTCACCCCACCAGTGCAGGCTGCCTATCAGAAAGTGGTGGCTGGTGTGGCTAATGCCCTGGCCCACAAGTATCACTAA
Mutated Translation (147 aa): MVHLTPEEKSAVTALWGKVNVDEVGGEALGRLLVVYPWTQRFFESFGDLSTPDAVMGNPKVKAHGKKVLGAFSDALAHLDNLKGTFATLSELHCDKLHVDPENFRLLGNVLVCVLAHHFGKEFTPPVQAAYQKVVAGVANALAHKYH
Shepherds Bush Changes to Protein
Shepherds Bush Physical Signs
• According to the variant database, this mutation manifests itself as an increase in oxygen affinity. It also results in a decreased bpg (2,3-dpg).
• Moreover, the mutation causes the hemoglobin to be unstable and hemolytic anemia
Schematic Diagram of Hb-Mainz
Val and Glu
Valine Glutamic Acid
Hb-Mainz Mutated Sequence• Mutated Nucleotide Sequence (444 nt):
ATGGTGCATCTGACTCCTGAGGAGAAGTCTGCCGTTACTGCCCTGTGGGGCAAGGTGAACGTGGATGAAGTTGGTGGTGAGGCCCTGGGCAGGCTGCTGGTGGTCTACCCTTGGACCCAGAGGTTCTTTGAGTCCTTTGGGGATCTGTCCACTCCTGATGCTGTTATGGGCAACCCTAAGGTGAAGGCTCATGGCAAGAAAGTGCTCGGTGCCTTTAGTGATGACCTGGCTCACCTGGACAACCTCAAGGGCACCTTTGCCACACTGAGTGAGCTGCACTGTGACAAGCTGCACGAGGATCCTGAGAACTTCAGGCTCCTGGGCAACGTGCTGGTCTGTGTGCTGGCCCATCACTTTGGCAAAGAATTCACCCCACCAGTGCAGGCTGCCTATCAGAAAGTGGTGGCTGGTGTGGCTAATGCCCTGGCCCACAAGTATCACTAA
Mutated Translation (147 aa): MVHLTPEEKSAVTALWGKVNVDEVGGEALGRLLVVYPWTQRFFESFGDLSTPDAVMGNPKVKAHGKKVLGAFSDALAHLDNLKGTFATLSELHCDKLHEDPENFRLLGNVLVCVLAHHFGKEFTPPVQAAYQKVVAGVANALAHKYH
Hb-Mainz Changes to Protein
Hb-Mainz Physical Effects
• According to the variant database, Hb-Mainz causes hemoglobin to become unstable and also causes hemolytic severe anemia.
Hb M-Saskatoon Mutation
M-Saskatoon Detailed Sequence• (Mutated) Nucleotide Sequence (444 nt):
ATGGTGCATCTGACTCCTGAGGAGAAGTCTGCCGTTACTGCCCTGTGGGGCAAGGTGAACGTGGATGAAGTTGGTGGTGAGGCCCTGGGCAGGCTGCTGGTGGTCTACCCTTGGACCCAGAGGTTCTTTGAGTCCTTTGGGGATCTGTCCACTCCTGATGCTGTTATGGGCAACCCTAAGGTGAAGGCTTATGGCAAGAAAGTGCTCGGTGCCTTTAGTGATGGCCTGGCTCACCTGGACAACCTCAAGGGCACCTTTGCCACACTGAGTGAGCTGCACTGTGACAAGCTGCACGTGGATCCTGAGAACTTCAGGCTCCTGGGCAACGTGCTGGTCTGTGTGCTGGCCCATCACTTTGGCAAAGAATTCACCCCACCAGTGCAGGCTGCCTATCAGAAAGTGGTGGCTGGTGTGGCTAATGCCCTGGCCCACAAGTATCACTAA
• (Mutated) Translation (147 aa): MVHLTPEEKSAVTALWGKVNVDEVGGEALGRLLVVYPWTQRFFESFGDLSTPDAVMGNPKVKAYGKKVLGAFSDGLAHLDNLKGTFATLSELHCDKLHVDPENFRLLGNVLVCVLAHHFGKEFTPPVQAAYQKVVAGVANALAHKYH
CAT becomes TATH becomes Y
Amino Acid Change
Histidine Tyrosine
→
3D Protein Sequence of Hemoglobin
Histidine is a positively charged hydrophilic amino acid
Tyrosine is an uncharged hydrophilic amino acid
What do you notice about where this mutation is near to?
We will come back to this…
M-Saskatoon, Methemoglobinemia
• Special class of low O2 affinity hemoglobin variant
• Iron in the heme is in an abnormal oxidation state
• Known as methemoglobin.– useless in O2 binding.
• Has a brown pigment• Causes cyanosis• Mutation may also cause
Dissociation of Dimers
Thalassemias Mutation of Initiation Codon ATG -> ATA beta0
• (Original) Nucleotide Sequence (444 nt): ATGGTGCATCTGACTCCTGAGGAGAAGTCTGCCGTTACTGCCCTGTGGGGCAAGGTGAACGTGGATGAAGTTGGTGGTGAGGCCCTGGGCAGGCTGCTGGTGGTCTACCCTTGGACCCAGAGGTTCTTTGAGTCCTTTGGGGATCTGTCCACTCCTGATGCTGTTATGGGCAACCCTAAGGTGAAGGCTCATGGCAAGAAAGTGCTCGGTGCCTTTAGTGATGGCCTGGCTCACCTGGACAACCTCAAGGGCACCTTTGCCACACTGAGTGAGCTGCACTGTGACAAGCTGCACGTGGATCCTGAGAACTTCAGGCTCCTGGGCAACGTGCTGGTCTGTGTGCTGGCCCATCACTTTGGCAAAGAATTCACCCCACCAGTGCAGGCTGCCTATCAGAAAGTGGTGGCTGGTGTGGCTAATGCCCTGGCCCACAAGTATCACTAA
• (Original) Translation (147 aa): MVHLTPEEKSAVTALWGKVNVDEVGGEALGRLLVVYPWTQRFFESFGDLSTPDAVMGNPKVKAHGKKVLGAFSDGLAHLDNLKGTFATLSELHCDKLHVDPENFRLLGNVLVCVLAHHFGKEFTPPVQAAYQKVVAGVANALAHKYH
• RED – Initiation Codon that changes to ATA which no longer begins the reading frame• Blue- Region of nucleotide base pairings, amino acids, and protein that is not read because of the
mutation to the START codon• Orange- Codon which becomes the START codon but originally is split into two codons before the
mutation. All subsequent amino acids change in the translation• Green- New Stop Codon
Amino Acid Change
Methionine Isoleucine
→
New Sequence Details
• (Mutated) Nucleotide Sequence (444 nt): ATGAAGTTGGTGGTGAGGCCCTGGGCAGGCTGCTGGTGGTCTACCCTTGGACCCAGAGGTTCTTTGAGTCCTTTGGGGATCTGTCCACTCCTGATGCTGTTATGGGCAACCCTAAGGTGAAGGCTCATGGCAAGAAAGTGCTCGGTGCCTTTAGTGATGGCCTGGCTCACCTGGACAACCTCAAGGGCACCTTTGCCACACTGAGTGAGCTGCACTGTGACAAGCTGCACGTGGATCCTGAGAACTTCAGGCTCCTGGGCAACGTGCTGGTCTGTGTGCTGGCCCATCACTTTGGCAAAGAATTCACCCCACCAGTGCAGGCTGCCTATCAGAAAGTGGTGGCTGGTGTGGCTAATGCCCTGGCCCACAAGTATCACTAA
• (Mutated) Translation (aa):MKLVVRPWAGCWWSTLGPRGSLSPLGICPLLMLLWATLR(STOP)
Hb Rocky Mountain
Sequence Detail of Hb Rocky Mountain
• (Mutated)Nucleotide Sequence (444 nt): ATGGTGCATCTGACTCCTGAGGAGAAGTCTGCCGTTACTGCCCTGTGGGGCAAGGTGAACGTGGTTGAAGTTGGTGGTGAGGCCCTGGGCAGGCTGCTGGTGGTCTACCCTTGGACCCAGAGGTTCTTTGAGTCCTTTGGGGATCTGTCCACTCCTGATGCTGTTATGGGCAACCCTAAGGTGAAGGCTCATGGCAAGAAAGTGCTCGGTGCCTTTAGTGATGGCCTGGCTCACCTGGACAACCTCAAGGGCACCTTTGCCACACTGAGTGAGCTGCACTGTGACAAGCTGCACGTGGATCCTGAGAACTTCAGGCTCCTGGGCAACGTGCTGGTCTGTGTGCTGGCCCATCACTTTGGCAAAGAATTCACCCCACCAGTGCAGGCTGCCTATCAGAAAGTGGTGGCTGGTGTGGCTAATGCCCTGGCCCACAAGTATCACTAA
• (Original)Translation (147 aa): MVHLTPEEKSAVTALWGKVNVVEVGGEALGRLLVVYPWTQRFFESFGDLSTPDAVMGNPKVKAHGKKVLGAFSDGLAHLDNLKGTFATLSELHCDKLHVDPENFRLLGNVLVCVLAHHFGKEFTPPVQAAYQKVVAGVANALAHKYH
GAT becomes GTT
Aspartic Acid (D) becomes Valine (V)
Amino Acid Change
Aspartic Acid Valine
→
Protein Structure and Description of Effects of Mutation
• Aspartic Acid is hydrophilic and negatively charged polar
• Valine is hydrophobic and non polar making it mildly unstable
• The change in the protein sequence may affect Hb function in cells as it causes an alteration in the protein shape
Effects of Hb Rocky Mountain
• Those with an Hb Rocky Mountain mutation (a.k.a. Hb Paddington) develop Microcytosis
• Smaller red blood cells• Those with mutation are at higher risk of
being anemic• Why do you think that is if the red blood cell
count is the same as a healthy person?
Useful Sites for Sheperds Bush/ Biblography
• http://globin.bx.psu.edu/cgi-bin/hbvar/query_vars3?mode=output&display_format=page&i=387
• http://globin.cse.psu.edu/html/huisman/variants/beta/Shepherds.Bush.html
• http://books.google.com/books?id=H85dwxYTKLwC&lpg=RA1-PA1623&ots=A9ufCRxiMW&dq=Shepherds%20Bush%20mutat&pg=RA1-PA1623#v=onepage&q=shepherds%20bush&f=false
Sources for Hb-Mainz
• http://www.umm.edu/blood/anehemol.htm• http://globin.bx.psu.edu/cgi-bin/hbvar/query_
vars3?mode=output&display_format=page&i=451
• http://www.ncbi.nlm.nih.gov/pubmed/17356397
Useful Sites of Hb Rocky Mountain
• http://globin.bx.psu.edu/cgi-bin/hbvar/query_vars3?mode=output&display_format=page&i=925
• http://www.pdb.org/pdb/explore/jmol.do?structureId=2HHB&bionumber=1
• http://en.wikipedia.org/wiki/Mean_corpuscular_volume
• http://en.wikipedia.org/wiki/Microcytosis
Sites On Hb M-Saskatoon
• http://web2.airmail.net/uthman/hemoglobinopathy/hemoglobinopathy.html
• http://www.ncbi.nlm.nih.gov/pubmed/7663000
• http://globin.bx.psu.edu/cgi-bin/hbvar/query_vars3?mode=output&display_format=page&i=359