The role of β-sheets in the structure and assembly of keratins

Fraser, R.D.B.

doi:10.1007/s12551-008-0005-0

Cited by 19 publications

(20 citation statements)

References 39 publications

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“…3 a, b). As many publications show, these three parts of feather keratin contain a 32-residue segment corresponding to the filament framework ( Fraser and Parry, 2009 , Fraser and Parry, 2008 ). Based on the amino acid composition of the filament framework segments in such keratin ( Fraser and Parry, 2008 ), each β-sheet includes four β-strands as illustrated in Fig.…”

Section: Essentials Of Keratin Biomass As Substrate For Keratinolyticmentioning

confidence: 99%

Microbial enzymes catalyzing keratin degradation: Classification, structure, function

Qiu

Wilkens

Barrett

et al. 2020

Biotechnology Advances

157

103

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Keratin is an insoluble and protein-rich epidermal material found in e.g. feather, wool, hair. It is produced in substantial amounts as co-product from poultry processing plants and pig slaughterhouses. Keratin is packed by disulfide bonds and hydrogen bonds. Based on the secondary structure, keratin can be classified into α-keratin and β-keratin. Keratinases (EC 3.4.-.- peptide hydrolases) have major potential to degrade keratin for sustainable recycling of the protein and amino acids. Currently, the known keratinolytic enzymes belong to at least 14 different protease families: S1, S8, S9, S10, S16, M3, M4, M14, M16, M28, M32, M36, M38, M55 (MEROPS database). The various keratinolytic enzymes act via endo -attack (proteases in families S1, S8, S16, M4, M16, M36), exo -attack (proteases in families S9, S10, M14, M28, M38, M55) or by action only on oligopeptides (proteases in families M3, M32), respectively. Other enzymes, particularly disulfide reductases, also play a key role in keratin degradation as they catalyze the breakage of disulfide bonds for better keratinase catalysis. This review aims to contribute an overview of keratin biomass as an enzyme substrate and a systematic analysis of currently sequenced keratinolytic enzymes and their classification and reaction mechanisms. We also summarize and discuss keratinase assays, available keratinase structures and finally examine the available data on uses of keratinases in practical biorefinery protein upcycling applications.

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Section: Essentials Of Keratin Biomass As Substrate For Keratinolyticmentioning

confidence: 99%

Microbial enzymes catalyzing keratin degradation: Classification, structure, function

Qiu

Wilkens

Barrett

et al. 2020

Biotechnology Advances

157

103

View full text Add to dashboard Cite

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“…A recent modeling analysis of the beta‐regions of representative sauropsid beta‐proteins has further clarified the nature of the chemical bonds at the origin of such stable beta‐regions, due to polar amino acids present in the region, to their site‐specific hydrogen and apolar chemical bonds that initially drive their association in dimers, which further pileup with rotational angles of approximately 45° into long linear polymers (Calvaresi et al., ). The characteristics that favor this type of polymerization are known also for other nonepidermal proteins containing beta‐sheet regions, where similar or more complex forms of beta sheets are present (Fraser and Parry, ). In conclusion, although they are both filamentous and fibrous proteins, IF‐keratins are not homologous to sauropsid beta‐proteins.…”

Section: Sauropsid Beta‐proteins Differ From If‐keratins and Are Bettmentioning

confidence: 99%

Sauropsids Cornification is Based on Corneous Beta‐Proteins, a Special Type of Keratin‐Associated Corneous Proteins of the Epidermis

Alibardi

2016

J Exp Zool Pt B

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The evolution of the process of cornification in amniote epidermis from the general process of keratinization present in simple epithelia of anamniotes took place through the evolution of specialized intermediate filament (α) keratins, keratin-associated proteins (KAPs) and corneous proteins (CPs). The scanty information on the three-dimensional conformation of known KAPs and CPs indicate these proteins contain α-helix, random coiled, or beta sheets with different lengths and organizations. CP genes originated in a chromosome locus indicated as epidermal differentiation complex (EDC), and transformed the epidermal keratinization of anamniotes into the cornified epidermis and skin appendages of amniotes (claws, beaks, and feathers). In particular, peculiar genes encoding for small proteins with a central region of 34 amino acids conformed as beta sheets were originated in the EDC of sauropsids (reptiles and birds). These proteins were traditionally indicated as beta-keratins because they form filaments of 3-4 nm in diameter and show an X-ray beta pattern. Different from other proteins of the EDC, dimers of these corneous beta-proteins associate into long polymers of filamentous proteins utilized in sauropsids skin appendages, such as scales and feathers. Future challenges in this area of research will be the study on gene regulation and expression for these proteins, their origin and evolution in different lineages of sauropsids, and their role in determining the material properties of sauropsid scales and other skin appendages.

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“…The members of the β-keratin superfamily ( 165 , 166 ) (not to be confused with the α-keratins in the intermediate-filament family) in reptiles and birds assemble into filaments via β-β interactions. Each monomer carries several short β-sheet domains, rich in V, I, and P ( 165 ) ( Text S8.21 ), and these serve as contact regions for dimerization. The dimers then polymerize to form long filaments, 3 to 4 nm in diameter, that are both viscoelastic and detergent insoluble, all features of the epiplastins.…”

Section: Discussionmentioning

confidence: 99%

Epiplasts: Membrane Skeletons and Epiplastin Proteins in Euglenids, Glaucophytes, Cryptophytes, Ciliates, Dinoflagellates, and Apicomplexans

Goodenough

Roth

Kariyawasam

et al. 2018

mBio

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Membrane skeletons associate with the inner surface of the plasma membrane to provide support for the fragile lipid bilayer and an elastic framework for the cell itself. Several radiations, including animals, organize such skeletons using actin/spectrin proteins, but four major radiations of eukaryotic unicellular organisms, including disease-causing parasites such as Plasmodium, have been known to construct an alternative and essential skeleton (the epiplast) using a class of proteins that we term epiplastins. We have identified epiplastins in two additional radiations and present images of their epiplasts using electron microscopy. We analyze the sequences and secondary structure of 219 epiplastins and present an in-depth overview and analysis of their known and posited roles in cellular organization and parasite infection. An understanding of epiplast assembly may suggest therapeutic approaches to combat infectious agents such as Plasmodium as well as approaches to the engineering of useful viscoelastic biofilms.

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The role of β-sheets in the structure and assembly of keratins

Cited by 19 publications

References 39 publications

Microbial enzymes catalyzing keratin degradation: Classification, structure, function

Microbial enzymes catalyzing keratin degradation: Classification, structure, function

Sauropsids Cornification is Based on Corneous Beta‐Proteins, a Special Type of Keratin‐Associated Corneous Proteins of the Epidermis

Epiplasts: Membrane Skeletons and Epiplastin Proteins in Euglenids, Glaucophytes, Cryptophytes, Ciliates, Dinoflagellates, and Apicomplexans

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