Hemoglobin Ancestors Offer Clues to Earliest Oxygen-Based Life [blow to Intelligent Design]

NewsWise ^ | 20 April 2004 | Staff

[PatrickHenry]

Red-blooded genealogists take note: The discovery in microbes of two oxygen-packing proteins, the earliest known ancestors to hemoglobin, brings scientists closer to identifying the earliest life forms to use oxygen.

According to the project’s lead investigator, University of Hawaii microbiologist Maqsudul Alam, the research may also aid in the search for blood substitutes as new molecular details shed light on how the structure of such proteins, called protoglobins, evolved to transport and release oxygen.

Scientists from the Maui High Performance Computing Center and the University of Texas Southwestern Medical Center contributed to the research. The findings will appear in the Proceedings of the National Academy of Sciences (PNAS) in an online “Early Edition” this week (at http://www.pnas.org) and in the April 27 print issue. A four-year, $500,000 grant from the National Science Foundation supported the project.

To life on primordial Earth, oxygen was poison. Within single-celled archaea, special proteins arose that captured and transported molecular oxygen, not to release it for respiration but to isolate and detoxify it to protect the organism. Archaea are a distinct group of microbes. Their lineage diverged long ago from a common ancestor they shared with bacteria and eukaryotes (plants, animals and other life forms that encase their DNA within a nucleus). Many strains of archaea exist, often in the planet’s harshest, hottest and oxygen-deprived environments. Some, however, adapted to use oxygen.

Alam’s research group found the two primitive protoglobulins in two different archaea species. One, Aeropyrum pernix, is limited to oxygen-based respiration, survives optimally in near-boiling saltwater, and was first discovered among thermal sea vents off Japan. The other, Methanosarcina acetivorans, uses several anaerobic – or oxygen-free – metabolic pathways that create methane gas. M. acetivorans is found in a wide range of realms, including lake-bottom muck, composting leaves, cow pies and human intestines. The genomes of both have recently been sequenced.

The ability to use oxygen for respiration allowed the diversity of life to expand vastly, an impact more fundamental, if perhaps not as dramatic, as the evolutionary transitions organisms made adapting from sea to land, from the ground to the air, or from “all fours” to upright.

Elizabeth Hood, who directs the areas of signal transduction and cellular regulation for NSF’s Division of Molecular and Cellular Biosciences, said, “As early life forms were established on earth, the atmosphere contained numerous toxic molecules, including nitric oxide and hydrogen sulfide. Early hemoglobins most likely evolved to bind and detoxify these gases. When oxygen became a component of the atmosphere, it was also toxic, and these early organisms used hemoglobin to bind and ultimately detoxify the oxygen.”

However, for advanced and larger life forms to exist in an oxygen-rich atmosphere on land, a mechanism was needed to take advantage of oxygen’s benefits, Hood said, and hemoglobins evolved into oxygen carriers rather than detoxifiers.

“Finding early hemoglobins in the most primitive life forms on earth testifies to their crucial role in the development of life as we know it today,” she said.

(In humans, with each breath in, hemoglobin binds oxygen in the lungs. Then, carried by blood cells made red by its oxygenated presence, the protein transports oxygen to tissues near and far in the body, where it then releases oxygen, which is essential to cellular respiration.)

To find the two protoglobins, the research team used advanced tools of biotechnology and high-performance computing, cloning genetic sequences from the two microbes and using specialized E. coli bacteria as gene-expression machinery to produce samples of the proteins. To analyze their structures, the team compared alignments with other members of the hemoglobin family of compounds. Computers generated models and created “molecular dynamic simulations” that illustrate with animations how the proteins bind with carbon monoxide, nitric oxide and oxygen.

Genetic sequences, binding characteristics and molecular structures of protoglobins were compared with those of hemoglobins and other oxygen-transport molecules from a wide range of organisms, including bacteria, tubeworms, roundworms, segmented “bloodworms,” mice, humans and sperm whales.

According to Alam, the similarities between these molecules and the protoglobins of A. pernix and M. acetivorans suggest “intriguing connections” between them and the evolution of mechanisms that sense oxygen, carbon monoxide, nitric oxide and hydrogen sulfide. These similarities, he said, also suggest connections to LUCA, short-hand for the “Last Universal Common Ancestor.”

“LUCA is believed to have been a metabolically ‘flexible’ single-celled organism with the ability to utilize oxygen for energy before free oxygen even existed in the air,” said Alam. “We think protoglobin helped give life to LUCA. And its descendents – hemoglobin, myoglobin, neuroglobin, and cytoglobin – allowed higher organisms to evolve” by allowing organisms to maintain a metabolic balance in an oxygenated world.

[PatrickHenry]

A link without which I would have been happier.

[<1/1,000,000th%]

Call Creationist Central. Time to raise the bar again.

[VadeRetro]

But what's the proof of that? Yada yada. This just SHOWS Intelligent Design because it was an experiment and people did it yada yada.

[PatrickHenry]

Observe how few of the creationist regulars have posted here up to now. So far, it's definitely the third stringers who have offered comments. I've observed this pattern before. It's known as "hiding under the bed and hoping the problem goes away." Eventually, some of them will drop in. Their comments will avoid the subject matter of the lead article, and instead will follow the usual diversionary paths: (1) lies, all lies; (2) Darwin was a communist-racist-queer-atheist-whatever; (3) Piltdown Man; (4) it takes more "faith" to believe in evolution ...; (5) yeah, but get your own dirt; (6) you're a horrible man, PatrickHenry!

[Modernman]

(1) lies, all lies; (2) Darwin was a communist-racist-queer-atheist-whatever; (3) Piltdown Man; (4) it takes more "faith" to believe in evolution ...; (5) yeah, but get your own dirt; (6) you're a horrible man, PatrickHenry!

(6) is generally their default setting.

[LiteKeeper]

YEC INTREP - where does it say that these microbes themselves were not designed by the Designer?

[Junior]

They very well might have been. However, after that evolution took over.

[LiteKeeper]

Matthew 19:4 And He answered and said, "Have you not read that He who created {them} [Adam and Eve] from the beginning MADE THEM MALE AND FEMALE,

[WhatsItAllAbout]

So you believe in evolution as a process where life evolved from inanimate matter into increasingly complex forms. Well, my question is what is the logical conclusion of this evolution? From our rung on the evolutionary ladder we can see the simpler life forms that have come before us, but what about higher forms of life? One who is a firm believer in evolution should only require a small leap of faith to believe that life could ultimately(if not already) evolve into a GOD like creature with supreme intelligence and power over the physical environment. If as a believer in evolution you disagree with this conclusion what would prevent this seemingly logical evolutionary conclusion? Is my logic flawed, if so please enlighten me? Thanks for your attention and I look forward to your responses.

[WhatsItAllAbout]

Bump

[balrog666]

Well, my question is what is the logical conclusion of this evolution?

Read a biology book - there is none.

From our rung on the evolutionary ladder we can see the simpler life forms that have come before us, but what about higher forms of life?

Higher? Lower? What does that mean?

The most successful form of life is still bacteria.

[Dimensio]

. If as a believer in evolution you disagree with this conclusion what would prevent this seemingly logical evolutionary conclusion?

My question is why a "GOD" like entity with "supreme intelligence" (you didn't define that term very well) and "power over the physical environment" (humans already have power over their physical environment, to some degree) would necessarily come about through changes in alelle frequency over time.

Evolution predicts only that creatures adapted to a given environment will survive and reproduce over successive generations. It makes no "conclusions" as to the changes that will occur to a species over time.

[Dimensio]

You forgot the comparison to Hitler. Hitler is the fun universal equivocation. When all of the facts are against you (or you just can't think of a proper rebuttal), claim that Hitler would have supported/did support the opponent's view and you "win".

[ScuzzyTerminator]

Is this what you're referring to?

... The only feature that is absolutely conserved in this subfamily of proteins is the histidine amino acid that binds to the heme iron.

Not specifically, just my memory from my old molbio textbooks. Anyway, ID does not expect that an irreducibly complex element be conserved absolutely, amino acid by amino acid, atom by atom, but that functional forms have a minimal complexity.


It is not unusual in proteins that an amino acid in a functional structure can be replaced by another amino acid. This does not make it a less complex structure. There may be many ways to make a heme group. The question ID asks is, "how simple can you make it?"

Nor is it expected that every functional structure be irreducibly complex but that there be found as many irreducibly complex structures as to make evolution improbable. I do not have an opinion as to whether the heme group is an especially complex structure, but the following, snipped from the University of Nebraska-Lincoln website:, makes it appear that even this small structure of a few amino acids, is remarkably fine tuned.

A frontal view of one heme group shows how the heme group binds the iron atom. The heme groups consists of carbon atoms (grey), nitrogen atoms (blue), oxygen atoms (red stick ends), the iron atom (red ball in the center), and hydrogen atoms (not shown).  Notice the blue nitrogen atoms (shown as sticks) directly contact the iron atom.  This is an illustration of the coordination mentioned above.
 
 
 
 
 

 

From this side view, it is evident (if you look closely) that the iron atom is slightly out of the plane formed by the heme group. This occurs in the absence of the sixth legand (for example O₂ or CO). The next image illustrates how the heme is attached to the peptide chain.
 
 
 

 

 
 
 

The amino acid histidine that coordinates to the iron atom is now rendered as a "sticks" model. The arrangement of 5 nitrogen atoms around the central iron atom in the coordination complex is called a tetragonal pyramid.
 
 
 
 
 
 

 
 
  When heme in hemoglobin binds another ligand (for example O₂) a new geometry results.  In this example, the oxygen molecule is bound directly opposite the nitrogen atom of the histidine group. In the oxy form of hemoglobin, there are 6 ligands to the iron atom. The result is an octahedral complex, that is the atoms around the central iron atom are arranged to form an octahedron.  Notice that the iron is now pulled into the plane of the heme group.

[WhatsItAllAbout]

balrog666 you make a good point about the limitations of natural selection, but evolution in theory is much more than natural selection. Form our stand point in evolutionary history (with the human geonome studies and the like) we are on the verge of taking control of our evolutionary(genetic) future. And with the advances in computer and other technologies the blending of man and machine will come about quickly. This combined/controlled evolution of man and machine in my mind is limitless.

[WhatsItAllAbout]

"... why a "GOD" like entity with "supreme intelligence" (you didn't define that term very well) and "power over the physical environment..."

Maybe I should restate the question why not "a "GOD" like entity with "supreme intelligence" ...and "power over the physical environment"

Is there any reason the evolutionary process could/would not eventually produce a "Supreme Being" which could possess the attributes of "GOD"? Especially in light of the possibility that man/machine may be able to direct thier future evolution? Thanks for all the responses.

[P-Marlowe]

[blow to Intelligent Design]

Non Sequitur

[Dimensio]

Is there any reason the evolutionary process could/would not eventually produce a "Supreme Being" which could possess the attributes of "GOD"?

I don't know. What are the attributes of "GOD"? You don't necessarily need to be exhaustive, but provide a good-sized list, and be specific with each entry on the list.

[WhatsItAllAbout]

For the details, see the "BIBLE". But for the sake of the discussion how about a being who can operate outside of our space time and has the ability to alter/suspend/negate the physics of our space time. The great "I AM" kind of sums up the idea of this hypothetical being.

[Dimensio]

But for the sake of the discussion how about a being who can operate outside of our space time and has the ability to alter/suspend/negate the physics of our space time.

That helps.

You could not even begin to predict the existence of a being coming about via evolution until you could demonstrate that such a being could exist in the first place. Even if you could demonstrate that such an entity could exist, you'd have to come up with a mechanism for a biological organism to posess those traits through inheretable mutation before you could claim that evolution could bring it about. Once there, you'd need to explain what selective pressures would be needed to create the potential for such a creature to evolve (though even that would not guarantee that such a creature would come about, as it's possible that none of the life forms in a given environment will go through the correct mutations)

Given what is currently known about biology, physics and chemistry, I'd say that it's not possible for such an entity to come about via evolution, or any other natural process.