Simultaneous binding of PA28 and PA700 activators to 20 S proteasomes

Hendil, Klavs B.; Khan, Selina; Tanaka, Keiji

doi:10.1042/bj3320749

Cited by 212 publications

(147 citation statements)

References 47 publications

Supporting

Mentioning

142

Contrasting

Unclassified

Order By: Relevance

“…The two ends of the cylindrically shaped 20S proteasome can bind either the same or different regulatory particles forming homogeneous or hybrid proteasomes respectively. 10,11,12,13 The PA200 activator was initially found in mammals 10 and electron microscopy (EM) studies showed that it binds to the ends of the 20S proteasome and opens the axial channel into the proteolytic cavity. 14 The PA200 sequence contains multiple HEAT-like repeats suggesting that the protein adopts a solenoid structure.…”

Section: Introductionmentioning

confidence: 99%

Structure of the Blm10–20 S Proteasome Complex by Cryo-electron Microscopy. Insights into the Mechanism of Activation of Mature Yeast Proteasomes

Iwanczyk

Sadre-Bazzaz

Ferrell

et al. 2006

Journal of Molecular Biology

View full text Add to dashboard Cite

The 20S proteasome is regulated at multiple levels including association with endogenous activators. Two activators have been described for the yeast 20S proteasome: the 19S regulatory particle and the Blm10 protein. The sequence of Blm10 is 20% identical to the mammalian PA200 protein. Recent studies have shown that the sequences of Blm10 and PA200 each contain multiple HEAT-repeats and that each binds to the ends of mature proteasomes, suggesting a common structural and biochemical function. In order to advance structural studies, we have developed an efficient purification method that produces high yields of stoichiometric Blm10-mature yeast 20S proteasome complexes and we constructed a three-dimensional (3D) model of the Blm10-20S complex from cryo-electron microscopy images. This reconstruction shows that Blm10 binds in a defined orientation to both ends of the 20S particle and contacts all the proteasome α subunits. Blm10 displays the solenoid folding predicted by the presence of multiple HEAT-like repeats and the axial gates on the α rings of the proteasome appear to be open in the complex. We also performed a genetic analysis in an effort to identify the physiological role of Blm10. These experiments, however, did not reveal a robust phenotype upon gene deletion, overexpression, or in a screen for synthetic effects. This leaves the physiological role of Blm10 unresolved, but challenges earlier findings of a role in DNA repair.

show abstract

Section: Introductionmentioning

confidence: 99%

Structure of the Blm10–20 S Proteasome Complex by Cryo-electron Microscopy. Insights into the Mechanism of Activation of Mature Yeast Proteasomes

Iwanczyk

Sadre-Bazzaz

Ferrell

et al. 2006

Journal of Molecular Biology

View full text Add to dashboard Cite

show abstract

“…The latter particle stimulates the peptidase but not the protease activity of the 20S proteasome (18). One 19S and one 11S particle can be bound to each end of the same 20S proteasome, a configuration of likely physiological significance (20,21). The 19S particle mediates the binding and ATP-dependent unfolding of a substrate protein before its transfer to the interior of the 20S core (17).…”

mentioning

confidence: 99%

RPN4 is a ligand, substrate, and transcriptional regulator of the 26S proteasome: A negative feedback circuit

Xie

Varshavsky

2001

Proc. Natl. Acad. Sci. U.S.A.

414

396

View full text Add to dashboard Cite

The RPN4 (SON1, UFD5) protein of the yeast Saccharomyces cerevisiae is required for normal levels of intracellular proteolysis. RPN4 is a transcriptional activator of genes encoding proteasomal subunits. Here we show that RPN4 is required for normal levels of these subunits. Further, we demonstrate that RPN4 is extremely short-lived (t 1/2 Ϸ2 min), that it directly interacts with RPN2, a subunit of the 26S proteasome, and that rpn4⌬ cells are perturbed in their cell cycle. The degradation signal of RPN4 was mapped to its N-terminal region, outside the transcription-activation domains of RPN4. The ability of RPN4 to augment the synthesis of proteasomal subunits while being metabolically unstable yields a negative feedback circuit in which the same protein up-regulates the proteasome production and is destroyed by the assembled active proteasome.proteolysis ͉ ubiquitin ͉ N-end rule ͉ UFD pathway ͉ cell cycle T he Saccharomyces cerevisiae RPN4 gene (its earlier names are SON1 and UFD5) (1) was originally identified through mutant rpn4 alleles that suppressed the growth defect of sec63-101 cells, which bore a temperature-sensitive (ts) variant of SEC63, an essential component of the protein translocation channel in the endoplasmic reticulum membrane (2). More recent studies have shown that mutations in RPN4 inhibit the degradation of normally short-lived proteins that are targeted by the N-end rule pathway, by the ubiquitin͞fusion͞degradation (UFD) pathway, and apparently also by other pathways of the ubiquitin (Ub)-proteasome system (3, 4). These findings suggested that the ability of rpn4 mutations to suppress the conditional lethality of sec63-101 may stem from stabilization of the mutant but partially active SEC63-101 against degradation at nonpermissive temperature.Regulated proteolysis by the Ub͞proteasome system plays essential roles in the cell cycle, differentiation, stress responses, and many other processes (5-7). Ub is a 76-residue protein whose covalent conjugation to other proteins marks these proteins for degradation by the 26S proteasome, an ATP-dependent multisubunit protease. Ub conjugation involves the formation of a thioester between the C terminus of Ub and a specific cysteine of the Ub-activating (E1) enzyme. The Ub moiety of E1ϳUb thioester is transesterified to a cysteine in one of several Ubconjugating (E2) enzymes. The Ub moiety of E2ϳUb thioester is conjugated via the isopeptide bond to the -amino group of either a substrate's Lys residue or a Lys residue of another Ub moiety, the latter reaction resulting in a substrate-linked multi-Ub chain (7,8). Most E2 enzymes function in complexes with proteins called E3 (9-11). The functions of E3s include the initial recognition of degradation signals (degrons) in substrate proteins, with different E3s recognizing different classes of degrons (12)(13)(14). The E2-E3 complexes, referred to as Ub ligases (this term is also used to denote E3s alone), mediate the formation of substrate-linked multi-Ub chains (15, 16). Ubiquitylated substrates are proce...

show abstract

“…3S The results are expressed as the means ± SD of three independent experiments. 1 The results were calculated by setting the determined minor absorbance (Gly samples) to 1 after considering the total 20S levels in both samples to be identical, as shown in Suppl. Data (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The 26S proteasome degrades proteins that have been modified by a poly-ubiquitin chain and that are involved in major cellular functions related to signaling, cell cycle regulation and homeostasis. The 26S proteasome is composed of a catalytic unit, termed the 20S proteasome (20S), 1 and the 19S regulatory unit, which is coupled to one or both sides of the 20S. The proteasome also exists in a form that is devoid of regulatory subunits, which is termed the free 20S.…”

Section: Introductionmentioning

confidence: 99%

“…The proteasome also exists in a form that is devoid of regulatory subunits, which is termed the free 20S. In mammalian and yeast cells, the 20S accounts for one-third of the total proteasome [1][2][3]. The degradation of oxidatively modified proteins is considered to be one of the major roles of the 20S [4][5][6], which is of importance because few repair systems for oxidatively modified amino acid residues exist.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

20S proteasome activity is modified via S-glutathionylation based on intracellular redox status of the yeast Saccharomyces cerevisiae: Implications for the degradation of oxidized proteins

Demasi

Hand

Ohara

et al. 2014

Archives of Biochemistry and Biophysics

View full text Add to dashboard Cite

Simultaneous binding of PA28 and PA700 activators to 20 S proteasomes

Cited by 212 publications

References 47 publications

Structure of the Blm10–20 S Proteasome Complex by Cryo-electron Microscopy. Insights into the Mechanism of Activation of Mature Yeast Proteasomes

Structure of the Blm10–20 S Proteasome Complex by Cryo-electron Microscopy. Insights into the Mechanism of Activation of Mature Yeast Proteasomes

RPN4 is a ligand, substrate, and transcriptional regulator of the 26S proteasome: A negative feedback circuit

20S proteasome activity is modified via S-glutathionylation based on intracellular redox status of the yeast Saccharomyces cerevisiae: Implications for the degradation of oxidized proteins

Contact Info

Product

Resources

About