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