Re: Comparative genomics of fungal allergens

[Guest guest]

Sharon,

This paper indicates that someone can become allergic to one or more

proteins(of a possible 20 or 30) in any given species of fungus and

develope antibodies for similar or identical proteins from other

species. It also suggests that some proteins are unique to particular

species.

Comparative genomics of fungal allergens and epitopes shows widespread

distribution of closely related allergen and epitope

Orthologues Bowyer*, Marcin Fraczek and W Denning

BMC Genomics 2006, 7:251 doi:10.1186/1471-2164-7-251

Public access free PDF at:

http://www.biomedcentral.com/content/pdf/1471-2164-7-251.pdf

Abstract:

Background: Allergy is a common debilitating and occasionally life

threatening condition. The fungal kingdom contains a number of species

that produce a wide range of well defined protein allergens although

the vast majority of fungal species have unknown allergenic potential.

The recent genome sequencing of a variety of fungi provides the

opportunity to assess the occurrence of

allergen orthologues across the fungal kingdom. Here we use

comparative genomics to survey the occurrence of allergen orthologues

in fungi. [An ortholog is a gene from a disparate species, so similar

in genetic sequence that it is assumed to have originated from a

single gene in a common ancestral species.]

Results: A database of 82 allergen sequences was compiled and used to

search 22 fungal genomes. Additionally we were able to model allergen

structure for representative members of several highly homologous

allergen orthologue classes. We found that some allergen orthologue

classes that had predicted structural congruence to allergens and

allergen epitopes were ubiquitous in all fungi. [An epitope is the

smallest part of an antigen that can be recognized by an antibody.]

Other allergen orthologues classes were less well conserved and may

not possess conserved allergen epitope orthologues in all fungi. A

final group of allergen orthologues, including the major allergens Asp

f 1 and Alt a 1, appear to be present in only a limited number of

species.

Conclusion: These results imply that most fungi may possess proteins

that have potential to be allergens or to cross react with allergens.

This, together with the observation that important allergens such as

Asp f 1 are limited to genera or species, has significant implications

for understating fungal sensitization, and interpreting diagnosis and

management of fungal allergy.

A few quotes from the article:

?A recent survey of fungal allergens (Bowyer unpublished observations)

shows that the best studied fungi may have up to 20 known well

characterised allergens (in the case of Aspergillus fumigatus,

Cladosporium herbarum and Alternaria alternata), between 27 and 60

other less well characterised IgE binding proteins as determined by

IgE binding to phage displayed allergen libraries [10-12] and another

20 proteins predicted to be allergen orthologues by virtue of close

homology to allergens known in other species (this publication). Thus

an estimated 0.5 ? 1% of proteins in a given fungal proteome may be

allergens. The known fungal allergens appear to occur as functional

groups such as serine proteases, heat shock proteins or thioredoxins

or orthologues of proteins such as Mn superoxide dismutase or enolase.

Reviews of allergen sensitization conducted in geographically diverse

areas suggest the most common causes of fungal sensitization

in populations are Aspergillus, Alternaria and Cladosporium spp. These

genera together with Penicillium are frequently among the most common

fungi encountered in surveys of airborne fungi in indoor and outdoor

environments worldwide [21-26].

.. . .we would suggest that the majority of proteins with >50% identity

have the potential to be cross-reactive or allergenic representing a

vast number of proteins in the fungal kingdom.

We note however that the various important allergen containing species

all possess subsets of major allergens such as Asp f 1, Alt a 1 and

Cla h 1 that are specific to species or at least genus. These

allergens would provide a species or genus specific diagnostic and are

already used in some cases.?

Jeff May

May Indoor Air Investigations

www.mayindoorair.com

[Guest guest]

Jeff,

A little deep for me, but I think I understand. Fungal proteins are key to

understanding acquired immune reactions to the molds that host (for lack of a

better word) these certain proteins. And..there appears to be enough

consistencies in the research of several proteins that some general rules should

be

able to be established about how they impact these acquired reactions.

Right?

Fungal proteins also play a key role in the activation of the production of

secondary metabolites, such as mycotoxins, as I understand it. Is that

right?

_http://news.cals.wisc.edu/newsDisplay.asp?id=1447_

(http://news.cals.wisc.edu/newsDisplay.asp?id=1447)

" The key to Keller’s approach lies in a single fungal protein called LaeA. A

few years ago, her team discovered that the presence of LaeA is required to

turn on the genes that manufacture secondary metabolites in Aspergillus

nidulans. “LaeA controls the production of secondary metabolites,†says

Keller. "

So, understanding how and why the fungal proteins do what they do, may hold

the key to understanding much about allergic, irritant and toxic reactions in

humans. Right?

Sharon

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fuel-efficient used cars.

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[Guest guest]

Sharon,

That is correct.

Ironically, we are loading up the indoor environment with microbial

proteins through the use of enzymes in cleaners. These products are

touted as being " green " and " organic " cleaners because they come from

living things (mostly bioengeneered bacteria).

Laundry detergents may contain up to 1% enzyme and some mold

remediators are using enzymes to clean mold. The most commonly used

enzyme in detergents is sublitisin, a protease (for digesting protein

such as blood stains).

Anyone with mold allergies should stay far away from laundry

detergents with enzymes, particularly powdered ones; always read the

label carefully (even if it's " green " ).

When Proctor and Gamble (manufacturer of TIDE, which is about 60% of

the detergent market)first starting using enzymes in detergent

formulations, they ended up with an almost 50% rate of occupational

asthma (from exposure to the enzyme dust).

A few years ago, P+G tested a bar soap with subtilisin, with the

notion that showering with the soap would facilitate elimination of

dead skin. They tested it for 6 months and abandoned the product after

too many users became sensitized to the enzyme-containing soap.

Depending on how you wash and dry clothing, significant residues of

detergent can be on clothing, sheets, etc. Thus you are exposed to the

chemicals 24/7.

May

Author, " Jeff May's Healthy Home Tips "

www.mayindoorair.com

________________________________________________________________________

> 8b. Re: Comparative genomics of fungal allergens

> Posted by: " snk1955@... " snk1955@... snk1955

> Date: Wed Jun 18, 2008 4:07 am ((PDT))

>

> Jeff,

>

> A little deep for me, but I think I understand. Fungal proteins are key to

> understanding acquired immune reactions to the molds that host (for

> lack of a

> better word) these certain proteins. And..there appears to be enough

> consistencies in the research of several proteins that some general

> rules should be

> able to be established about how they impact these acquired reactions.

> Right?

>

> Fungal proteins also play a key role in the activation of the production of

> secondary metabolites, such as mycotoxins, as I understand it. Is that

> right?

>

> _http://news.cals.wisc.edu/newsDisplay.asp?id=1447_

> (http://news.cals.wisc.edu/newsDisplay.asp?id=1447)

>

> " The key to Keller´s approach lies in a single fungal protein called LaeA. A

> few years ago, her team discovered that the presence of LaeA is required to

> turn on the genes that manufacture secondary metabolites in Aspergillus

> nidulans. " LaeA controls the production of secondary metabolites, "

> says Keller. "

>

> So, understanding how and why the fungal proteins do what they do, may hold

> the key to understanding much about allergic, irritant and toxic reactions in

> humans. Right?

>

> Sharon

>

>

[Guest guest]

GREAT information . Thanks.

 

Chris...