The Function Of The Human Mitochondrial Chaperonin

sHSPs are a ubiquitous class of chaperones found across all kingdoms of life. sHSP range in size from 12-42 kilo Daltons in large oligomers of 12 to >32 subunits and the structure is homologous across all species. The sHSP monomer consists of three domains: a disordered N-terminal arm, a beta-sandwich α-crystallin domain, and a flexible C-terminal extension. The N-terminal domain is the most variable region with little conservation between species. Experimental evidence also suggests N-terminal involvement in substrate binding and protection. The α-crystallin domain is the most highly conserved region and adopts a β-sandwich conformation composed of 7 to 8 anti-parallel β-strands (Basha et al, 2012). The C-terminus contains an I-X-I motif, which helps to satblizie the oligomeric form of the sHSP (Basha et al, 2012).

For the methods used in this experiment refer to the following from UFV BIO 202 Lab #2: Investigation of Heat Shock Protein Gene Expression using Western Blotting (2017).

Chaperones are proteins that ensure the correct folding of the CFTR within the endoplasmic reticulum. Hsp70 is an important cytosolic chaperone that complexes with CFTR and reduces aggregation [5]. The CFTR passes through the endoplasmic reticulum-associated degradation (ERAD) after folding in the ER. This quality control system involves the ubiquitin proteasome system (UPS) for which CFTR is a substrate [16]. If a protein is molded and targeted for degradation, then ubiquitin will covalently attach to lysine residues on the CFTR. Three enzymes are required for the process of ubiquitylation: E1 ubiquitin activating enzymes, E2 ubiquitin conjugating enzymes, and E3 ubiquitin protein ligases. E1 enzymes are activated through hydrolysis of ATP, which creates an activated ubiquitin that is transferred to an E2 active site. The activated ubiquitin is then covalently bound to a lysine on the protein by an E3 ligase. A polyubiquitin chain is then formed as ubiquitin molecules link together, and if there are four or more then the misfolded CFTR chain is removed form the ER membrane and targeted for degradation by the 26S proteasome

The amino acid sequences derived from decoding the mRNA determines a protein's final conformation, helper proteins aid the newly formed polypeptide with its folding to achieve a proper functional shape. These molecular chaperones are essential as the cytoplasm is often filled with new polypeptide chains and thus these accumulation of polypeptide chain might accumulate together and fold into a non-function shape. Example of well studied chaperones from E.Coli are DnaK, DnaJ, GroEL and GroES. And GrpE.

Alzheimer’s disease is a neurodegenerative illness caused by the accumulation of misfolded, and immature, proteins in the endoplasmic reticulum (ER) of the cell. Aggregation of misfolded proteins in this region produces neurofibrillary tangles that correlated to loss of memory in patients. Mutations in the Amyloid Precursor Protein (APP) have displayed direct causes of increased concentration of β-amyloid, which are involved in the production of the neurofibrillary tangles. Chaperone protein, GRP78 in the endoplasmic reticulum increases availability to assist in protein folding, and prevention of aggregation upon sense of ER stress signals, however mutations such as the PS1 mutant of the APP have been found to overcome this function. PS1 is

There may also be sections where the secondary structure is neither helix nor sheet. Then the structure is called a random structure, indicating that it folds in random directions. The amino acids in an alpha helix are arranged in a right-handed helical structure resembling a spring. The alpha helix is the most common form of regular secondary structure in proteins. The beta-sheet is the second form of regular secondary structure in proteins consisting of beta strands connected laterally by three or more hydrogen bonds, forming a generally twisted, pleated sheet. The beta-sheet is sometimes called the beta pleated sheet since sequential neighboring atoms are alternately above and below the plane of the sheet giving a pleated appearance. Turns are the third of the three "classical" secondary structures that serve to reverse the direction of the polypeptide chain. They are located primarily on the protein surface and accordingly contain polar and charged residues. However, they are not very common in discussions of protein structure today.

PINK1 (PTEN Induced Putative Kinase 1) is a gene that provides directions for making the protein PTEN induced putative kinase 1. The greatest amounts of this protein can be found in the muscles, heart, and testes, but it is also found in cells throughout the body. The protein lies within the mitochondria of the cell, and, although the function of PTEN induced putative kinase 1 is not yet fully understood, it seems to assist in protecting the mitochondria from becoming impaired when the cell is under stress. In order for PTEN induced putative kinase 1 to help the mitochondria, it needs to first function properly itself. Two specialized regions of this protein ensure that it does this. One of these regions, the mitochondrial targeting motif, serves as the delivery address. In other words, once the protein is created, the mitochondrial targeting motif makes sure that it gets to the mitochondria. The other region, the kinase domain, most likely executes the proteins protective function.

. The 3-D tertiary structure of polypeptide proteins globular and is the result of interactions that occur between R groups. Tertiary structure is a result of the bonds between sidechains of amino acids, the R groups. The structure and bonds involve alpha helices, beta pleated sheets, and also regions unique to each protein. Tertiary proteins are held together by four different types of forces; hydrogen bonds, hydrophobic interactions (including Van der Waals interactions), ionic bonding (electrostatic interactions), and disulfide bridges (strong covalent bonds). Hydrogen bonds occur within and between polypeptide chains and the aqueous environment. Hydrogen bonding forms between a highly electronegative oxygen atom or a nitrogen atom and a hydrogen atom attached to another oxygen atom or a nitrogen atom. This links the amino acid

addition, there seem to be several hydrogen bonds between the protein and the phosphate backbone of the DNA such as the oxygen in the phosphate group at position 33.

Until recent years, the mitochondrial genome, located in the mitochondrion, and the genetic information encoded by it have been given little attention. However, recently it became apparent that the mitochondrial genome, despite its small size, is crucial for the study of human evolution and disease, as mtDNA mutations lead to some serious diseases.

A protein’s tertiary structure, the compact, biologically active and most stable form of the protein, results from further folding of the amino acid chain. The environment in which a protein is synthesized and allowed to folded is a significant determinant of its final shape. If the tertiary structure of a protein is disrupted, the protein is said to be denatured, and it loses its activity. Based on their tertiary structure, proteins can be classified as globular, fibrous and membrane proteins. Globular proteins participate in sophisticated processes such as enzyme-mediated catalysis, transport of molecules, signal transduction, defense and regulation.

Introduction: The goal of this experiment was to practice using the FirstGlance in Jmol molecular visualization to examine key structural features of proteins. This work is important because protein structure can be related to function, multiple-sequence alignments and evolutionary preservation, and designing drug. FirstGlance in Jmol makes it fairly easy to perceive structure-function relationships in the protein you chose. Using FirstGlance, it is easy to visualize and distinguish chains, and disulfide bonds are obvious. Alpha helices and beta strands are evident due to the "cartoon" secondary structural schematic.

Bettelheim, Brown, Campbell and Farrell assert that polypeptide chains do not extend in straight lines but rather they fold in various ways and give rise to a large number of three-dimensional structures (594). This folding or conformation of amino acids in the localized regions of the polypeptide chains defines the secondary structure of proteins. The main force responsible for the secondary structure is the non-covalent

The endoplasmic reticulum (ER) is an essential organelle that is a major place for the biogenesis of cellular components including proteins, lipids, and carbohydrates and internal calcium storage. ER is primarily responsible for protein translocation, protein folding and protein post modification. Proper folding of protein in the ER is accomplished with the aid of ER resident proteins or enzymes such as chaperones. Binding of chaperones to

Molecular chaperones stabilize unfolded or misfolded proteins until native conformations have been obtained to promote cell survival during and after stress conditions. They do not change or add to the folding principles encoded by a protein because polypeptide chains inherently carry within them all the information that is necessary for achieving the native state of a protein. Instead, they optimize the folding process by stabilizing folding intermediates and are involved in every aspect of proteome maintenance including de novo folding, refolding of stress-induced misfolded proteins, and targeting proteins for degradation (Hartl 2009, Hartl 2011). Chaperones, many of which are induced or upregulated only during stress conditions, work in cooperative networks when protein-aggregate concentration